leetcode

0 class Solution {

1 public:

2 long long numberOfWays(const string &s) const {

3 static int count[100001];

4 const int n = size(s);

5 int crnt[] = {0, 0};

6 long long res = 0;

7

8 for (int i = n - 1; i >= 0; i--) {

9 const int idx = s[i] - '0';

10 count[i] = crnt[!idx];

11 crnt[idx]++;

12 }

13

14 crnt[0] = crnt[1] = 0;

15 for (int i = 0; i < n; i++) {

16 const int idx = s[i] - '0';

17 res += count[i] * crnt[!idx];

18 crnt[idx]++;

19 }

20

21 return res;

22 }

23 };