Number of Substrings Containing All Three Characters LeetCode solution in C++

1
class Solution {
2
 public:
3
  int numberOfSubstrings(string s) {
4
    int i = 0, j = 0;
5
    int n = s.size();
6
    map<char, int> mp;
7
    int count = 0;
8
    while (j < n) {
9
      mp[s[j]]++;
10
      if (mp.size() < 3) {
11
        j++;
12
      } else {
13
        while (mp.size() == 3) {
14
          count += (n - j);
15
          mp[s[i]]--;
16
          if (mp[s[i]] == 0) mp.erase(s[i]);
17
          i++;
18
        }
19
        j++;
20
      }
21
    }
22
    return count;
23
  }
24
};