语法练习

#include <iostream>
#include <vector>

using namespace std;
char op;

int main(int argc, char** argv) {
  cin >> op; 
  vector<vector<float>> grid(12, vector<float>(12));
  for (int y = 0; y < 12; ++y)
    for (int x = 0; x < 12; ++x) cin >> grid[y][x];

  int cnt = 0;
  float sum = 0.0;
  for (int y = 0; y < 11; ++y)
    for (int x = y + 1; x < 12; ++x) {
      ++cnt;
      sum += grid[y][x];
    }

  if (op == 'M') printf("%.1f", sum / cnt);
  else printf("%.1f", sum);

  return 0;
}