奶牛碑文。

#include

using namespace std;

int main() {

int n;

cin >> n;

long long num = 0;

int b = 0, e = 0;

char s[100010];

int i;

int a[100010] = { 0 };

int cnt = 0;

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

cin >> s[i];

if (s[i] == 'C') {

cnt++;

}

a[i] = cnt;

}

cnt = 0;

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

if (s[i] == 'W') {

cnt++;

}

else if (s[i] == 'O') {

num += cnt * a[i];

}

}

cout << num;

}