Leetcode 389 Find the Difference

Leetcode 389 Find the Difference

#include <vector>
#include <string>
using namespace std;
class Solution {
public:
char findTheDifference(string s, string t) {
vector<int> lettercount(26,0);

for(int i = 0;i < s.length();i ++)
{
lettercount[s[i] - 'a'] ++;
}
for(int i = 0; i < t.length();i ++)
{
lettercount[t[i] - 'a'] --;
if(lettercount[t[i] - 'a'] < 0)
return t[i];
}

}
char findTheDifference1(string s, string t) {
char c = 0;
for(int i = 0;i < s.length();i ++)
{
c ^= s[i];
}
for(int i = 0; i < t.length();i ++)
{
c ^= t[i];
}
return c;

}
char findTheDifference2(string s, string t) //to learn
{
char c = 0;

for (auto ch : s) c ^= ch;
for (auto ch : t) c ^= ch;

return c;
}
};