24点游戏

http://acm.hdu.edu.cn/showproblem.php?pid=1427

不传引用会TLE

#include <bits/stdc++.h>

using namespace std;

double epx = 1e-10;
int cmp = 24;

bool judge(vector<int> &nums) {
  if (nums.size() == 1) {
    if (nums[0] == cmp) return true;
    return false;
  }
  
  for (int i = 0; i < nums.size(); ++i) {
    for (int j = i + 1; j < nums.size(); ++j) {
      vector<int> t;
      for (int k = 0; k < nums.size(); ++k) {
        if (k != j && k != i) t.push_back(nums[k]);
      }
      int a = nums[i], b = nums[j];
      t.push_back(a - b);
      if (judge(t)) return true;
      t.pop_back();
      
      t.push_back(b - a);
      if (judge(t)) return true;
      t.pop_back();
      
      t.push_back(b * a);
      if (judge(t)) return true;
      t.pop_back();
      
      t.push_back(b + a);
      if (judge(t)) return true;
      t.pop_back();
      
      if (a != 0 && b % a == 0) {
        t.push_back(b / a);
        if (judge(t)) return true;
        t.pop_back();
      }
      
      if (b != 0 && a % b == 0) {
        t.push_back(a / b);
        if (judge(t)) return true;
        t.pop_back();
      } 
    }
  }
  return false;
}
char a[22][22];
int char2double(char ch) {
    if (ch == 'A') return 1;
    else if (ch == 'J') return 11;
    else if (ch == 'Q') return 12;
    else if (ch == 'K') return 13;
    else if (ch == '1') {
        return 10; 
    } else return ch - '0';
}
void work() {
    vector<int> vc;
    for (int i = 0; i < 4; ++i) {
        vc.push_back(char2double(a[i][0]));
    }
    if (judge(vc)) {
        printf("Yes
");
    } else printf("No
");
}

int main() {
    // freopen("data.txt", "r", stdin);
    while (scanf("%s%s%s%s", a[0], a[1], a[2], a[3]) > 0) work();
    return 0;
}

还有这题不是小数的，小数的话可以用eps简单模拟

#include <bits/stdc++.h>

using namespace std;

double epx = 1e-5;
double cmp = 24.0;

bool judge(vector<double>& nums) {
  if (nums.size() == 1) {
    if (fabs(cmp - nums[0]) < epx) return true;
    return false;
  }
  
  for (int i = 0; i < nums.size(); ++i) {
    for (int j = i + 1; j < nums.size(); ++j) {
      vector<double> t;
      for (int k = 0; k < nums.size(); ++k) {
        if (k != j && k != i) t.push_back(nums[k]);
      }
      double a = nums[i], b = nums[j];
      t.push_back(a - b);
      if (judge(t)) return true;
      t.pop_back();
      
      t.push_back(b - a);
      if (judge(t)) return true;
      t.pop_back();
      
      t.push_back(b * a);
      if (judge(t)) return true;
      t.pop_back();
      
      t.push_back(b + a);
      if (judge(t)) return true;
      t.pop_back();
      
      if (fabs(a - 0) > 10 * epx) {
        t.push_back(b / a);
        if (judge(t)) return true;
        t.pop_back();
      }
      
      if (fabs(b - 0) > 10 * epx) {
        t.push_back(a / b);
        if (judge(t)) return true;
        t.pop_back();
      } 
    }
  }
  return false;
}

void work() {
  double a, b, c, d;
  cin >> a >> b >> c >> d;

  vector<double> vc;
  vc.push_back(a);
  vc.push_back(b);
  vc.push_back(c);
  vc.push_back(d);
  if (judge(vc)) cout << "true" << endl;
  else cout << "false" << endl;
}

int main() {
    work();
    return 0;
}

https://www.nowcoder.com/questionTerminal/fbc417f314f745b1978fc751a54ac8cb

这题莫名奇妙wa