题解 | #24点游戏算法#

#include <math.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
const int target =24;
const double EPSILON = 1e-6;
int solve(double*l,int len)
{
    if(len == 1)
    {
        return fabs(l[0]-target) < EPSILON;
    }
    int size = len;
    for(int i=0;i<size;i++)
    {
        for(int j=0;j<size;j++)
        {
            if(i!=j){
                double list2[20];
                int len2 = 0;
                for(int k=0;k<size;k++)
                {
                    if(k!=i && k!=j)
                    {
                        list2[len2++] = l[k];
                    }
                }

                for(int k=0;k<4;k++)

                {
                    if(k<2&&i>j)
                    {
                        continue;
                    }
                    if(k==0)
                    {
                        list2[len2++] = l[i]+l[j];
                    }else if(k==1)
                    {
                        list2[len2++] = l[i]*l[j];
                    }else if(k==2)
                    {
                        list2[len2++] = l[i] -l[j];
                    }else if(k==3)
                    {
                        if(fabs(l[j])<EPSILON) continue;
                        list2[len2++] = l[i] / l[j];
                    }
                    if(solve(list2, len2))
                    {
                        return true;
                    }
                    len2--;
                }
            }
        }
    }
    return false;
}
int main() {
    double l[4] = {0};
    for(int i=0;i<4;i++)
    {
        scanf("%lf %lf %lf %lf",&l[0],&l[1],&l[2],&l[3]);
        
    }
    int flag =0;
        flag = solve(l,4);;
        if(flag == 1)printf("true");
        else {
            printf("false");
        }
}