题解 | #24点游戏算法#

#include <any>
#include <iostream>
#include <type_traits>
#include <vector>
using namespace std;

bool flag = false;
void dfs(vector<int>& v, int sum, int idx) {
    if (idx == v.size() && sum == 24) {
        flag = true;
    }
    for(int i=idx;i<v.size();i++){
        swap(v[i], v[idx]);
        int oldsum=sum;
        sum = oldsum + v[idx];
        dfs(v, sum, idx+1);
        sum = oldsum - v[idx];
        dfs(v, sum, idx+1);
        sum = oldsum * v[idx];
        dfs(v, sum, idx+1);
        sum = oldsum / v[idx];
        dfs(v, sum, idx+1);
        swap(v[i], v[idx]);
    }
}
int main() {
    vector<int> vv;
    int t;
    while (cin>>t) {
        vv.push_back(t); 
    }
    for(int i=0;i<vv.size();i++){
        swap(vv[i], vv[0]);
        dfs(vv, vv[0], 1);
        swap(vv[i], vv[0]);
    }
    cout<<(flag?"true":"false");
}
// 64 位输出请用 printf("%lld")