Print all combinations of an array java. You may return the answer in any order.

Print all combinations of an array java Jul 23, 2025 · Permutations are like the magic wand of combinatorics, allowing us to explore the countless ways elements can be rearranged within an array. Please see the below link for a solution that prints only distinct permutations even if Sep 29, 2025 · The idea is to use backtracking to explore all possible choices one by one recursively. I posted it as none of the answers here give a clear algorithm, and I can't stand recursion. Apr 14, 2024 · For better understanding, we will illustrate it using Java Program below: Example - 1 In this Java Program, we will print all the possible permutations of string using a recursion or backtracking approach. permutation for ba, would be ba and ab, but what about longer string such as abcdefgh? Is there any Java implementation example? Sep 12, 2025 · Given a positive integer `n`, print all combinations of numbers between 1 and `n` having sum `n`. One of the most popular programming problems is to create every conceivable string combination. So using the idea of power sets, and ordered permutations of the guava library, im able to obtain an array of all the combinations of elements inside my original array. e. Jul 23, 2025 · ABC ACB BAC BCA CBA CAB Algorithm Paradigm: Backtracking Time Complexity: O (n*n!) Note that there are n! permutations and it requires O (n) time to print a permutation. The notion of permutation relates to the act of permuting, or rearranging, members of a set into a particular sequence or order (unlike combinations, which are selections that disregard order). He is B. May 17, 2019 · In the above solution, it is possible to get all the combinations without repeating the same number using given set of numbers to sum up to the given value. Feb 2, 2024 · Similarly, we create an empty array and use the Pascal identity problem to generate all the possible combinations of an array. {1, 2} is the same as {2, 1} so we have to deal with repetitions. Then Jul 23, 2025 · The idea is to start from an empty output string (we call it prefix in following code). Using recursion and backtracking all the combinations can be printed. We want to find all unique combinations in arr that sum up to 7. Jul 23, 2025 · Your All-in-One Learning Portal: GeeksforGeeks is a comprehensive educational platform that empowers learners across domains-spanning computer science and programming, school education, upskilling, commerce, software tools, competitive exams, and more. Apr 28, 2015 · 0 Print all the combinations of elements in matrix of size m * n. First, we’ll define what a permutation is. Tech from IIT and MS from USA. Another important factor is from which index you will start making the subset of size k. Examples: For n = 1, the program should print following: 1 For n = 2, the program should print following: 1 1 2 For n = 3, the program should print following: 1 1 1 1 2 2 1 3 For n = 4, the program should print following: 1 1 1 1 1 1 2 1 2 1 1 3 Mar 12, 2012 · Having problems trying to show every combination of a character of array without repeating letters. Combination Just like permutation value, getting combination value is very easy in Java but to get all the combination of array, list, and set elements is more difficult than getting permutations. That way we can avoid printing permutations. As far as I know combination means that the order does not matter, i. . Mar 3, 2024 · We keep printing the combinations until no new combinations can be found. Adjust the input lists as needed. print all combination without repetition of three letter and four letter word | icse java | computer Learn Easily - By Anurag 2. Sep 14, 2025 · Write code to print all combinations of positive integers in increasing order that sum to a given positive number. it means: given an array I need to have all subsets (all subsets of 1 element, all subset of 2 element, all subset of n elements) an of each subset all possible permutations. How to manipulate the algorithm below to get all possible combinations including repetitive numbers to sum up to the given value? May 29, 2012 · Second, you should think in the digits/alphanumeric chars like a position of an array and build your sets by using the array indexes, making sure there's no repeated set, after that start creating your combinations and make sure you haven't used one of them. We maintain a visited array to track which elements are already included in the current permutation. The entered string will be converted into a character array using the toCharArray () function and will be passed into the solve function. For 3 and 4 arrays we can write 3 and 4 loops respectively but for several arrays it is difficult to write that many loops. To do so, create an array of string res [] to store the substrings of string s and an empty string cur to store the current string. In the context of computer science and programming, “ string combinations ” refer to the various ways in which you can arrange or select characters from a given string. in); Apr 26, 2025 · Start with an empty array temp [] that stores the current combination being constructed. I need to get all possible combinations of an array of Arguments, for instance the array could look like this [Integer, several arrays. We also make the current indices 0 in all the arrays to the right of this array. Store all permutations. Whether you're a coder, a math enthusiast, or someone on a quest to solve a complex problem, understanding how to generate all permutations of an array is a valuable skill. can you please suggest me the algorithm? e. java If we select an integer to print, make currentLength +1 and if we ignore, dont change currentLength. Sep 20, 2021 · I have an array of numbers say [1,2,3,1,1000] , now I want to get all possible combinations of this array and calculate its sum. When the machine is called, it outputs a combination and move to the next one. Jan 8, 2011 · How would you go about testing all possible combinations of additions from a given set N of numbers so they add up to a given final number? A brief example: Set of numbers to add: N = {1,5,22,15,0 Sep 26, 2025 · Given an array arr [] of integers and an integer target, find all unique combinations of elements where the sum of the chosen elements is equal to target. Practice this problem We can use recursion to solve this problem. At each function in the stack, you should increase the indexes in the indexes array to produce the correct output. This task can be efficiently performed using a backtracking approach, which allows the system to try every possibility while reverting back to previous states when necessary. It’s a tricky question and asked mostly in Java interviews. Starting from the rightmost array we check if more elements are there in that array. Hello, I am trying to determine an elegant and efficient manner to find all the possible combinations of the elements in an array of Integers. Algorithm: Nov 23, 2021 · Three arrays are used, input [] array which has the characters, count [] array has the count of characters and result [] is a temporary array which is used in recursion to generate all the combinations. Jul 12, 2025 · To output the combination, we loop through the index array and the values of the integer array are the indexes of the input array. This video explains the intuition and process behind finding combination of r elements in an array of size n. L12. Jun 15, 2016 · 21 Consider the combination as a binary sequence, if all the 4 are present, we get 1111 , if the first alphabet is missing then we get 0111, and so on. I know that if the length of the array is n then there are n! possible combinations. I need all combinations. Examples: Nov 6, 2011 · Hmm maybe you can clarify one thing in your question: the array 1,1,1,1,1,2,3,4,5,6 would be one of those combinations? Or is every number within that array only one time allowed? Mar 7, 2021 · I need to write a program to print all sub arrays of an array in a particular format. Saurabh. Dec 14, 2018 · I have the two arrays: String [] operators = {"+", "-", "*"}; int [] numbers = {48, 24, 12, 6}; And I want to get all possible combination in a String format like Aug 18, 2014 · This is my working solution for the following problem: given an array of integers of size n, print all possible combinations of size r. Note: A combination is a selection of items where the order does not matter. This is a very important interview backtracking problem. Algorithm for Permutation of a String in Java We will first take the first character from the String and permute with the remaining chars. Given a total score of n, print out all the combinations to compose n. There are a few ways to do this with Java, including repetition, and recursion. We use an array to store combinations and we recursively fill the array and recurse with reduced number. In this method, we consider the elements of the given array and recure using the two cases. util. Example 1: Input: n = 4, k = 2 Output: [[1,2],[1,3],[1,4],[2,3],[2,4],[3,4]] Explanation: There are 4 choose 2 = 6 total combinations. When I call the function to start it off, I initialized that indexes array to all 0s. Nov 8, 2021 · A quick guide to print all permutations of a string in java and new java 8 api. Jun 14, 2019 · 3 You can consider this approach: Every combination is a result of removing a value from the initial array until the desired length is reached. User first enters the element in the set and then actual elements. If k reaches 0, it means k elements have been selected, we temp array to final result. Example- I/o: n = 3 A = (1,2,3) where n is the size of the array and A is the array itself. Dec 8, 2022 · Given a string str, the task is to print all the permutations of str. This is a java program to generate and print all the permutation of the Numbers. For each element, there two options, either include it into subset or exclude it. If yes, we increment the entry for that array in indices i. Below is the implementation of the above approach. E. What Is a Permutation? Jun 17, 2023 · Explore recursive and iterative algorithms for generating all k-combinations of a set. Jul 23, 2025 · Follow the below steps to solve the problem: Generate all possible permutations that can be created with 1 character, which is the given array arr []. 2K subscribers 57 May 10, 2024 · Suppose we have an array arr = { 1, 2, 3, 3, 5 }, the length of the array n = 5, and the target sum k = 7. Combinations are valid such that two combinations have different subset of elements. We first sort the array so that duplicates are adjacent. if you take this array as an example [1, 2, 3, 4, 5], you would first remove 1 value at a time from it and get the following resulting arrays : Mar 24, 2015 · Notice how I have the function combinations (). At each recursion level, we iterate through the array: Skip already visited elements. Find all combinations of size r in the array. So for n alphabets we'll have 2^n -1 (since 0 is not included) combinations. Auxiliary Space: O (r - l) Note: The above solution prints duplicate permutations if there are repeating characters in the input string. So far we have solved so many questions around printing all elements, subsequ Apr 6, 2020 · Print all combinations of java array containig different words Asked 4 years, 9 months ago Modified 4 years, 9 months ago Viewed 38 times Jul 23, 2022 · You can win three kinds of basketball points, 1 point, 2 points, and 3 points. Problem Statement In the “Print all Possible Combinations of R Elements in a given Array of size N” problem, we have given an array of size n. For example, if n = 4 and k = 2, the output would be {1, 2}, {1, 3}, {1, 4}, {2 I want to implement this in JAVA, so if you want to make use of the Collections class in JAVA no problem :) To be more clear: the input always consist of a even number of elements so all pairs in one list together are all elements in the input. + Ncn = 2 Pow N So you get 2 Pow N combinations for given word of length N characters. Names must oc. java * Execution: java Combinations n * * Enumerates all subsets of n elements using recursion. Jan 23, 2012 · Simplest way of calculating the possible combinations of strings is here Mathematically to find R combinations in a given lot of N = NcR So what we are finding here is, all possible combinations = Nc0 + Nc1 . Oct 26, 2017 · Java Programming - Print all possible combinations of r elements in a given array of size n - Mathematical Algorithms - Given an array of size n and r is 2. By exploring different ways to rearrange the characters of a string, you gain insights into the complexity and efficiency of various algorithmic approaches. But I'm having a very hard time figuring out how to write an algorithm that will only ou May 31, 2022 · I did see this and this post on it, but it is not in Java or Kotlin, so it doesn't help me. Would the following code be able to do that? We have to print all the permutations of a given string in java using recursion. Given two arrays, where array one has variables and array two contains the variable's values, I want to get all possible combinations of those two arrays, for example: Oct 15, 2025 · Problem Statement # Given a positive integer, target, print all possible combinations of positive integers that sum up to the target number. e ab,abc,abcd. I've seen several similar questions about how to generate all possible combinations of elements in an array. Combination Sum - Given an array of distinct integers candidates and a target integer target, return a list of all unique combinations of candidates where the chosen numbers sum to target. Now, in your binary sequence produced, if the code is 1 , then the element is present otherwise it is not included. Jun 19, 2013 · I needed all unique combinations of multiple arrays for my use case in a lexicographical order. For every character added, print all possible strings with current prefix by recursively calling for k equals to k-1. Jul 3, 2012 · This video lecture is produced by IITian S. I am able to write it using n nested loops, but Can you solve this real interview question? Combinations - Given two integers n and k, return all possible combinations of k numbers chosen from the range [1, n]. What is an elegant way to find all the permutations of a string. Start from the 0th index and for each index ind, add the current character s [ind] in the string cur, and add the string cur in res []. Now, coming to the problem, I want to be able to create all the possible combinations for an array. After that, we swap the elements back to get all the Permutation of the array. Note: Each element in the array can be used at most once in the combination. For each element, it either includes it in the current combination or skips it, based on the value of k (The number of elements left to be included in the combination). public static String[] getAllLists(String[] elements, int lengthOfList) Sep 29, 2025 · The idea is to generate all distinct permutations using recursion and backtracking. Given an array. If you are trying to understand the Java Program, then you should know Array uses in Java and For loop concepts I was trying to print all possible combinations of an array in python without itertools and stumbled up on this piece of beautiful code, I can't even understand it enough to use it, please can someone help me understand this Given two numbers, n and K, write a program to find all possible combinations of K numbers from 1 to n. It may switch columns though. Print all Permutations of a String/Array | Recursion | Approach - 1 take U forward 911K subscribers Subscribe Sep 15, 2025 · The program should print all the distinct combinations, while preserving the relative order of elements as they appear in the array. Now I have working code thanks for that. Jul 12, 2025 · Given an array of strings arr [], for every string in the array, print all possible combinations of strings that can be concatenated to make that word. - Every combination should have number of elements equal to number of Aug 11, 2024 · Print All Possible Number Combinations Whose Sum is 10: The program InterviewPrograms55 aims to find pairs of numbers in a given sequence that add up to 10. How can this algorithm be written? Update: thanks, but I need a pseudo code algorithm like: Feb 13, 2015 · I'm working on a problem in Java to find all possible combinations given an arbitrary starting array, by decrementing the values one at a time of each item in the array until the value 1 is reached Sep 15, 2025 · Given an integer array, find all distinct combinations of a given length `k`, where the repetition of elements is allowed. Nov 20, 2020 · I am trying to print all combinations of size r in an array size n, but i don't have output. My goal is to get as many of the sub-array combinations from this one array and print the output. A combination is a selection of items from a larger set, where the order of the selected items doesn’t matter. If the list has too few elements, don't print anything. g int n = {1,2,3} and its combinations are 123,132,231,213,312,321 problem is that i want the general algorithm which is independent of the array size. May 17, 2023 · Writing a Java program to print all permutations of a string is an excellent way to understand and apply recursive algorithms. You may return the combinations in any order. Note: This is an excellent problem for learning problem-solving using the inclusion and exclusion principle of combinatorics and backtracking. Method 1: Using Recursion AllCombinations. Edit: I have look to all answer. Once stored, generate all possible permutations of 2 characters and store them. The invariant used in the solution is that each combination will always be stored in increasing order of elements involved. You can return the answer in any order. If an array of size n is given, then it will take O (n 2) time to perform the task. Your task is to generate and print all possible combinations of exactly r elements from this array. And third, we’ll look at three ways to calculate them: recursively, iteratively, and randomly. The iterative method acts as a state machine. The idea is to add each element to the output and recur for the remaining items with one less element. Sep 26, 2024 · The time complexity analysis for Combination Now, let’s say, given an array of size n, we are asked to take r elements from the array and perform combinations of r elements. Aug 31, 2015 · I’ve got one array like so: [1,2,4,5,1]. 2. g. This needs to include duplicates, so abcd is not the same as dcba The purpose is to find all combinations and check if if can make the same combination from a different array. *; class Main { public static void main (String [] args) { Scanner sc=new Scanner (System. This function takes the original array as a parameter, and a second array for tracking indexes. May 20, 2025 · You are given an array arr [] consisting of n elements. Print all possible combinations of an array. The following representation clears things up. Then This program will print all possible combinations of the provided ArrayList<ArrayList<String>>. For example A,B,C,D ha Can you solve this real interview question? Permutations - Given an array nums of distinct integers, return all the possible permutations. It takes an input array of integers and looks for all combinations of two numbers whose sum is equal to 10. We will examine many approaches to producing every possible combination of a given string in this section. Also, if we want to remove the duplicate entry, then, We need to perform the following Aug 18, 2014 · I want to solve the following problem: given an array of size n, print all combinations of size r. To avoid printing permutations, construct each tuple in the same order as array elements. May 2, 2013 · Hi, I have an integer array and i want to print all the combinations of this integer array. Sample Example: 1 3 5 2 6 7 Expected Output: 2 , 1 2 , 3 2 , 5 6 , 1 6 , 3 6 , 5 7 , 1 7 , 3 7 , 5 Rules: - Every combination starts from bottom of matrix and proceeds towards top. Jan 17, 2014 · Here's what I am trying to do: Given a list of names, print out all combinations of the names taken three at a time. When i used code coverage tool in eclipse, it shows that: My for block that is supposed to print the Sep 24, 2008 · This version maintains a single array of indices to define a mapping between the list of all values and the values for the current combination, i. A permutation is an arrangement of all or part of a set of objects, with regard to the order of the arrangement. Aug 31, 2025 · All combinations of abc can be represented by all binary representation from 0 to (2^n - 1) where n is the size of the string . I have come to a sudden stop in the development of an application of mine. Oct 20, 2015 · What is the best way in Java to make recursive function to get all combinations of elements taken from several sets of candidates? In general the number of candidate sets is undefined so recursive solution seems to be appropriate for this task. Mar 13, 2018 · I have an array that contains letters and numbers and I want to find all possible combination of array elements. Learn how to generate all possible combinations of elements from an array in Java, complete with code examples and explanations. My initial attempt is: Generate all Combinations With Sum Equal to Target Problem focuses on identifying possible combinations of numbers within set that add up to given target sum. Example: Aug 9, 2023 · PROBLEM STATEMENT Given an array of size n, generate and print all possible combinations of r elements in array. Note that combinations are unordered, i. Jul 11, 2025 · In this post, an iterative method to output all combinations for a given array will be discussed. Oct 3, 2025 · Given an array arr [] of distinct integers and an integer target, find all unique combinations of array where the sum of chosen element is equal to target. In this post, you will learn how to write a program to find all possible combinations of String in Java. The same number may be chosen from candidates an unlimited number of times. Sep 24, 2025 · Your All-in-One Learning Portal: GeeksforGeeks is a comprehensive educational platform that empowers learners across domains-spanning computer science and programming, school education, upskilling, commerce, software tools, competitive exams, and more. moves to the next element in that array. Once the last step is completed, discard all permutations of a single character. The same element may be chosen any number of times to make target. Comments 1 Description print all combination of r elements in a given array Likes 1,401Views Apr 22 Aug 3, 2022 · Popular topics In this tutorial, we will learn how to find the permutation of a String in a Java Program. For example, there are six permutations of the set {1 Aug 11, 2022 · /****************************************************************************** * Compilation: javac Combinations. State Space Tree for printing all subsets using Backtracking: Suppose an array of size 3 having elements [1, 2, 3], the state space tree can be constructed as below: Feb 20, 2017 · 0 Suppose I have this array: [a,b,c,d] How would I go about finding every possible combination i. Below is the implementation of above idea : May 27, 2010 · int a[] = new int[]{3,4,6,2,1}; I need list of all permutations such that if one is like this, {3,2,1,4,6}, others must not be the same. For a combination of r elements from an array of size n, a given element may be included or excluded from the combination. To generate all combinations of array values setup nested loops to organize all pairs, triples, etc in a systematic manner. The following image illustrates the iteration in the algorithm. , [1,2] and [2,1 Generating all possible combinations in Java involves using recursion to explore each subset of a given array. Jan 9, 2019 · In this article, we’ll look at how to create permutations of an array. Write code to print all permutations of elements of that array-----------------------------------------Join our 30-days online course to prep Feb 14, 2025 · [Interesting Approach] - Using Recursion The idea is to recursively generate all possible substrings of the given string s. For example, if we are given input ‘5’, these are the possible sum combinations. 001 -> "c" 010 -> "b" Jul 23, 2025 · The idea is to use recursion. Before I proceed to the solution, I have the following quest Apr 28, 2015 · Right now I'm trying to write a function that takes an array and an integer n, and gives a list of each size n combination (so a list of int arrays). etc. Nov 6, 2024 · 34 35 36 import java. Second, we’ll look at some constraints. Ensure that each unique group of r elements is printed only once, regardless of order. If you represent 1 to (2 Pow N) integers in binary, and place your char in the place where 1 Given a set {1,2,3,4,5n} of n elements, we need to find all subsets of length k . I do not want to use the Combinations formula, which uses Factorials. You may return the answer in any order. Note : We can also take zero into consideration which will eventually give us an empty set "", the only change in code will be starting loop from zero. We can apply similar ideas to solve other problems. One by one add all characters to prefix. We’ll focus on the implementation in Java and, therefore, won’t go into a lot of mathematical detail. constantly uses O (k) additional space during the entire runtime. For e Mar 20, 2023 · Find ALL possible combinations of the elements in an Array. I want to do this through code to produce the sets. dah zfz pnhh dxxpe mecda gbvlzx uqk yqfhos wrardojd wjacv uxjgtsc zcod ftq hlue qmrapq