CC1.3

permutation.java

import java.io.*;
import java.util.*;

class permutation {
    public static void main(String[] args) {
        String str1 = "abc";
        String str2 = "cba";
        if(permutation(str1, str2))
            System.out.println("They are each other's permutation");
        else
            System.out.println("They are not each other's permutation");
    }

    public static boolean permutation(String str1, String str2) {
        int[] count = new int[256];
        int len1 = str1.length();
        int len2 = str2.length();
        if(len1 != len2)
            return false
        boolean success =true;
        for(int i = 0; i < len1; i++) {
            count[str1.charAt(i)] ++;
        }
        for(int i = 0; i < len2; i ++) {
            count[str1.charAt(i)] --;
        }
        for(int i = 0; i < 256; i ++) {
            if(count[i] != 0)
                success = false;
        }

        return success;
    }
}

A small mistake at line 25, “str1.charAt(i)” should be "str2.charAt(i)", otherwise it always returns "true" when “len1 == len2”.