Given two strings s and t which consist of only lowercase letters.

String t is generated by random shuffling string s and then add one more letter at a random position.

Find the letter that was added in t.

Example:

Input:
s = "abcd"
t = "abcde"Output:
eExplanation:
'e' is the letter that was added.

 

//既然都是小写字母 那么用之前的数组也是解决的
//这种方法与使用map是相同的
public static char findTheDifference(String s, String t) {int[] arr = new int[26];for (int i = 0; i < t.length(); i++) {arr[t.charAt(i) - 'a']++;}for (int i = 0; i < s.length(); i++) {--arr[s.charAt(i)-'a'];}for (int i =0;i< arr.length;i++){if(arr[i]>0){return (char)(i+'a');}}return ' ';
}

 

//原来还可以这么写呀
public static char findTheDifference2(String s, String t) {char c = 0;for (int i = 0; i < s.length(); ++i) {c ^= s.charAt(i);}for (int i = 0; i < t.length(); ++i) {c ^= t.charAt(i);}return c;
}

 

//写的看上去简略一点 少循环一次
public static char findTheDifference3(String s, String t) {int n = t.length();char c = t.charAt(n - 1);for (int i = 0; i < n - 1; ++i) {c ^= s.charAt(i);c ^= t.charAt(i);}return c;
}

 

git：https://github.com/woshiyexinjie/leetcode-xin