A. 扑克牌

直接去重后拿52减去数量即可

#include <bits/stdc++.h>
using namespace std;
int n;
vector<string> s;
int main() {
  cin >> n;  
  for (int i = 1; i <= n; i++) {
    string t;
    cin >> t;
    s.push_back(t);
  }
  sort(s.begin(), s.end());
  cout << 52 - (unique(s.begin(), s.end()) - s.begin());
  return 0;
}

B. 地图探险

简单模拟，对着题目写就行

#include <bits/stdc++.h>
using namespace std;
int t, w[4][2] = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}};
int n, m, k, x, y, d;
bool vis[1010][1010];
char g[1010][1010];
int main() {
  cin >> t;
  while (t--)
  {
    cin >> n >> m >> k;
    cin >> x >> y >> d;


    for (int i = 1; i <= n; i++)
      for (int j = 1; j <= m; j++) {
        vis[i][j] = 0;
        cin >> g[i][j];
      }
    int ans = 1;
    vis[x][y] = true;
    for (int i = 1; i <= k; i++)
    {

      int tx = x + w[d][0], ty = y + w[d][1];
      if (tx >= 1 && tx <= n && ty >= 1 && ty <= m && g[tx][ty] == '.') {
        x = tx, y = ty;
        if (!vis[x][y])
          vis[x][y] = true, ans++;
      }
      else
        d = (d + 1) % 4;
    }
    cout << ans << '\n';
  }
  return 0;
}

C. 小木棍

一开始想贪心，想了想先打个表，结果一打表直接就很明显能看出规律了

#include <bits/stdc++.h>
using namespace std;

string solve(int n)
{
  if (n <= 1)
    return "-1";
  if (n == 2)
    return "1";
  if (n == 3)
    return "7";
  if (n == 4)
    return "4";
  if (n == 5)
    return "2";
  if (n == 6)
    return "6";
  if (n == 7)
    return "8";
  if (n == 8)
    return "10";
  if (n == 9)
    return "18";
  if (n == 10)
    return "22";

  int t = n % 7;

  if (t == 0)
    return string(n / 7, '8');
  if (t == 1)
    return "10" + string(n / 7 - 1, '8');
  if (t == 2)
    return "1" + string(n / 7, '8');
  if (t == 3)
    return "200" + string(n / 7 - 2, '8');
  if (t == 4)
    return "20" + string(n / 7 - 1, '8');
  if (t == 5)
    return "2" + string(n / 7, '8');
  if (t == 6)
    return "6" + string(n / 7, '8');
  return "-1";
}

int main() {
  int t;
  cin >> t;
  while (t--)
  {
    int n;
    cin >> n;
    cout << solve(n) << '\n';
  }

  return 0;
}

D. 接龙

还没做，占坑