leetcode刷题系列-389. Find the Difference

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.

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class Solution {
public:
char findTheDifference(string s, string t) {
int lens = s.size();
int lent = t.size();
map<char,int> s_m;
for(int i = 0; i < lens; ++i)
{
if(s_m.find(s[i]) != s_m.end())
s_m[s[i]]++;
else
s_m[s[i]] = 1;
}
for(int i = 0; i < lent; ++i)
{
if(s_m.find(t[i]) == s_m.end())
{

return t[i];
}
else
{
s_m[t[i]]--;
if(s_m[t[i]] < 0)
return t[i];
}
}
return t[0];
}
};