gold-1-2

给定两个由小写字母组成的字符串 s1 和 s2，请编写一个程序，确定其中一个字符串的字符重新排列后，能否变成另一个字符串。

示例 1：

输入: s1 = "abc", s2 = "bca"
输出: true 

示例 2：

输入: s1 = "abc", s2 = "bad"
输出: false

说明：

• 0 <= len(s1) <= 100
• 0 <= len(s2) <= 100

//leetcode submit region begin(Prohibit modification and deletion)
class Solution {
    public boolean CheckPermutation(String s1, String s2) {
        if (s1 == null && s2 == null) {
            return true;
        }

        if (s1 == null ||  s2 == null) {
            return false;
        }

        if (s1.length() == 0 && s2.length() == 0) {
            return true;
        }

        if (s1.length() != s2.length()) {
            return false;
        }

        int[] arr1 = new int[26];
        int[] arr2 = new int[26];

        for (char ch : s1.toCharArray()) {
            arr1[ch - 'a']++;
        }
        for (char ch : s2.toCharArray()) {
            arr2[ch - 'a']++;
        }

        for (int i = 0; i < 26; i++) {
            if (arr1[i] != arr2[i]) {
                return false;
            }
        }

        return true;
    }
}
//leetcode submit region end(Prohibit modification and deletion)