华为OJ（24点游戏）

#include<iostream>
using namespace std;
int cal(int a,int b,int c,int d,int i,int j,int k)
{
int sum=0;
if(i==0)sum=a+b;
else if(i==1)sum=a-b;
else if(i==2)sum=a*b;
else if(i==3)sum=a/b;

if(j==0)sum=sum+c;
else if(j==1)sum-=c;
else if(j==2)sum*=c;
else if(j==3)sum/=c;

if(k==0)sum+=d;
else if(k==1)sum-=d;
else if(k==2)sum*=d;
else if(k==3)sum/=d;

return sum;
}
bool find24Points(int a, int b, int c, int d)
{
int i,j,k;
for(i=0;i<4;i++)
for(j=0;j<4;j++)
for(k=0;k<4;k++)
{
if(cal(a,b,c,d,i,j,k)==24) return true;
if(cal(a,b,d,c,i,j,k)==24)return true;
if(cal(a,c,b,d,i,j,k)==24)return true;
if(cal(a,c,d,b,i,j,k)==24)return true;
if(cal(a,d,b,c,i,j,k)==24)return true;
if(cal(a,d,c,b,i,j,k)==24)return true;
if(cal(b,a,c,d,i,j,k)==24)return true;
if(cal(b,a,d,c,i,j,k)==24)return true;
if(cal(b,c,a,d,i,j,k)==24)return true;
if(cal(b,c,d,a,i,j,k)==24)return true;
if(cal(b,d,a,c,i,j,k)==24)return true;
if(cal(b,d,c,a,i,j,k)==24)return true;
if(cal(c,a,b,d,i,j,k)==24)return true;
if(cal(c,a,d,b,i,j,k)==24)return true;
if(cal(c,b,a,d,i,j,k)==24)return true;
if(cal(c,b,d,a,i,j,k)==24)return true;
if(cal(c,d,a,b,i,j,k)==24)return true;
if(cal(c,d,b,a,i,j,k)==24)return true;
if(cal(d,a,b,c,i,j,k)==24)return true;
if(cal(d,a,c,b,i,j,k)==24)return true;
if(cal(d,b,a,c,i,j,k)==24)return true;
if(cal(d,b,c,a,i,j,k)==24)return true;
if(cal(d,c,a,b,i,j,k)==24)return true;
if(cal(d,c,b,a,i,j,k)==24)return true;

}
return false;
}

int main()
{

int a,b,c,d;
cin>>a;
cin>>b;
cin>>c;
cin>>d;
if(find24Points(a,b,c,d))
cout<<"true"<<endl;
else
cout<<"false"<<endl;
//system("pause");
return 0;
}