Objective: Given a String, print all the permutations of it.
Input: A String
Output: Print all the permutations of a string
Example:
Input : abc Output: abc acb bac bca cba cab Approach:
- Take one character at a time and fix it at the first position. (use swap to put every character at the first position)
- make recursive call to rest of the characters.
- use swap to revert the string back to its original form fo next iteration.
Complete Code:
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| import java.util.*; | |
| import java.lang.*; | |
| import java.io.*; | |
| public class StringPermutations { | |
| private char[] arrA; | |
| public void permutation(char[] arrA, int left, int size) { | |
| int x; | |
| if (left == size) { | |
| for (int i = 0; i < arrA.length; i++) { | |
| System.out.print(arrA[i]); | |
| } | |
| System.out.print(" "); | |
| } else { | |
| for (x = left; x < size; x++) { | |
| swap(arrA, left, x); | |
| permutation(arrA, left + 1, size); | |
| swap(arrA, left, x); | |
| } | |
| } | |
| } | |
| public void swap(char[] arrA, int i, int j) { | |
| char temp = arrA[i]; | |
| arrA[i] = arrA[j]; | |
| arrA[j] = temp; | |
| } | |
| public static void main(String[] args) throws java.lang.Exception { | |
| // your code goes here | |
| String s = "abc"; | |
| char[] arrCh = s.toCharArray(); | |
| StringPermutations i = new StringPermutations(); | |
| i.permutation(arrCh, 0, arrCh.length); | |
| } | |
| } |
Output :
abc acb bac bca cba cab
use simple string based program as below
public class StringPermutations {
public static void main(String[] args) {
String s = “abcd”;
StringPermutations i = new StringPermutations();
i.permute(“”, s);
}
private void permute(String newString, String oriString) {
if (oriString == null || oriString.isEmpty()) {
System.out.println( newString);
}
for (int i = 0; i < oriString.length(); i++) {
permute(newString.concat(oriString.substring(i, i + 1)), oriString
.substring(0, i).concat(oriString.substring(i + 1)));
}
}
}
nice post .visit string top program collection
Hello Team,
It is a nice work.
One suggestion to this post: We do not need second swap and when left and size are equal then just print the string. we do need to iterate with for loop