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Permute.java
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Permute.java
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/* Author: Nthabiseng Mashiane
Date: 5 December 2017
Code to create permutations of strings*/
import java.util.*;
public class Permute{
public static ArrayList<ArrayList<String>> permute(String[] extensions) {
ArrayList<ArrayList<String>> result = new ArrayList<ArrayList<String>>();
permute(extensions, 0, result);
return result;
}
static void permute(String[] extensions, int start, ArrayList<ArrayList<String>> result) {
if (start >= extensions.length) {
ArrayList<String> words = new ArrayList<String>(Arrays.asList(extensions));
result.add(words);
}
for (int j = start; j <= extensions.length - 1; j++) {
swap(extensions, start, j);
permute(extensions, start + 1, result);
swap(extensions, start, j);
}
}
public static void swap(String[] a, int i, int j) {
String temp = a[i];
a[i] = a[j];
a[j] = temp;
}
}