#### Permute String

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```package com.thealgorithms.strings;

/*
Backtracking algorithm used in the program:-

>>Fix a character in the first position and swap the rest of the character with the first character.
Like in ABC, in the first iteration three strings are formed: ABC, BAC, and CBA by swapping A with
A, B and C respectively.
>>Repeat step 1 for the rest of the characters like fixing second character B and so on.
>>Now swap again to go back to the previous position. E.g., from ABC, we formed ABC by fixing B
again, and we backtrack to the previous position and swap B with C. So, now we got ABC and ACB.
>>Repeat these steps for BAC and CBA, to get all the permutations.
*/
public final class PermuteString {
private PermuteString() {
}

// Function for swapping the characters at position I with character at position j
public static String swapString(String a, int i, int j) {
char[] b = a.toCharArray();
char ch;
ch = b[i];
b[i] = b[j];
b[j] = ch;
return String.valueOf(b);
}

public static void main(String[] args) {
String str = "ABC";
int len = str.length();
System.out.println("All the permutations of the string are: ");
generatePermutation(str, 0, len);
}

// Function for generating different permutations of the string
public static void generatePermutation(String str, int start, int end) {
// Prints the permutations
if (start == end - 1) {
System.out.println(str);
} else {
for (int i = start; i < end; i++) {
// Swapping the string by fixing a character
str = swapString(str, start, i);
// Recursively calling function generatePermutation() for rest of the characters
generatePermutation(str, start + 1, end);
// Backtracking and swapping the characters again.
str = swapString(str, start, i);
}
}
}
}
```