LeetCode oj 389. Find the Difference(Hash）

389. Find the Difference

Question
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Total Accepted: 22851
Total Submissions: 46129
Difficulty: Easy

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:
e

Explanation:
'e' is the letter that was added.

给你两个字符串s和t，t比s多了一个字符，问这个字符是什么。

可以用数组做Hash，也可以用HaspMap，但是java的Map数组我调了好久都不对，还是C++好用感觉= =+，最后还是用数组模拟的

public class Solution {
public char findTheDifference(String s, String t) {
int a[] = new int [26];
int len_s = s.length();
int len_t = t.length();
for(int i=0;i<len_s;i++){
a[s.charAt(i)-'a']++;
}
for(int i=0;i<len_t;i++){
a[t.charAt(i)-'a']--;
if(a[t.charAt(i)-'a'] == -1){
return t.charAt(i);
}
}
return ' ';
}
}