蒟蒻求助

#include<bits/stdc++.h>
using namespace std;
char c[5]={' ','+','-','*','/'} ;
int a[5];
int f(int x,int y,int k)
{
	if(k==1) return x+y;
	if(k==2) return abs(x-y);
	if(k==3) return x*y;
	return(y==0||x<y||x%y!=0) ?-9999999 :x/y;
}
void print(int a,int b,int m,int n,int x,int y,int i,int j,int k)
{
	printf("%d%c%d=%d\n",max(a,b),c[i],min(a,b),f(a,b,i));
	printf("%d%c%d=%d\n",max(m,n),c[j],min(m,n),f(m,n,j));
	printf("%d%c%d=%d\n",max(x,y),c[k],min(x,y),f(x,y,k));
	exit(0);
}
int main()
{
	for(int i=1;i<=4;i++) scanf("%d",&a[i]);
	sort(a+1,a+5);
	while(next_permutation(a+1,a+5))
	{
		for(int i=1;i<=4;i++)
		{
			for(int j=1;j<=4;j++)
			{
				for(int k=1;k<=4;k++)
				{
					if(  f  (  f  (    f  (  a[1],a[2],i  )    ,  a[3]  ,  j  )  ,a[4]  ,k)==24)
					{
						print(a[1] , a[2] , f(a[1],a[2],i) ,a[3], f(f(a[1],a[2],i),a[3],j), a[4] ,i,j,k);
					} 
					else if(   f(f(a[1],a[2],i),f(a[3],a[4],j),k)==24    )
					{
						print(a[1]  ,a[2],   a[3]  ,a[4]  ,f(a[1],a[2],i), f(a[3],a[4],j) ,i,j,k );
					}
				}
			}
		}
	}
	printf("No answer!");
	return 0;
}