问题描述
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.
解题代码
利用 hashtable 计数，大于 0 表示在 s 中出现，小于 0 表示该字符在 t 中出现的次数多于在 s 中出现的次数。
class Solution {
public:
char findTheDifference(const string &s, const string &t) {
map<char, int> m;
for (size_t i = 0; i < s.length(); i++) {
m[s[i]]++;
}
for (size_t i = 0; i < t.length(); i++) {
if (--m[t[i]] < 0) {
return t[i];
}
}
return 0;
}
};