纯凭感觉写的题，居然过了

#include <iostream>
#include <vector>

using namespace std;
int k;

bool check(vector<vector<int>>& grid, int n) {
  for (int y = 1; y <= n; ++y) {
      int cnt = 0;
      for (int x = 1; x <= n; ++x) cnt += grid[y][x];
      if (cnt != 1) return false; 
  }

  for (int y = 1; y <= n; ++y) {
    for (int x = 1; x <= n; ++x) {
      int cx, cy;
      if (grid[y][x]) {
        cx = x + 1, cy = y + 1; // 向右下角走
        while (cx >= 1 && cx <= n && cy >= 1 && cy <= n) {
          if (grid[cy][cx]) return false;
          cx += 1, cy += 1;
        }

        cx = x - 1, cy = y - 1; // 向左上角走
        while (cx >= 1 && cx <= n && cy >= 1 && cy <= n) {
          if (grid[cy][cx]) return false;
          cx -= 1, cy -= 1;
        }

        cx = x + 1, cy = y - 1; // 向右上角走
        while (cx >= 1 && cx <= n && cy >= 1 && cy <= n) {
          if (grid[cy][cx]) return false;
          cx += 1, cy -= 1;
        }

        cx = x - 1, cy = y + 1; // 向左下角走
        while (cx >= 1 && cx <= n && cy >= 1 && cy <= n) {
          if (grid[cy][cx]) return false;
          cx -= 1, cy += 1;
        }
      }
    }
  }

  return true;
}

int main(void) {
  cin >> k;
  while (k--) {
    int n;
    cin >> n;
    vector<vector<int>> grid(n + 1, vector<int>(n + 1, 0));
    for (int x = 1; x <= n; ++x) {
        int y;
        cin >> y;
        grid[n - y + 1][x] = 1;
    }

    puts(check(grid, n) ? "YES" : "NO");
  }

  return 0;
}