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洛谷

``````//24点2.0
#include<bits/stdc++.h>
using namespace std;
int a[10],b[10],x[10],y[10];
void sc()
{
	for(int i=1;i<=3;i++)
	{
		if(x[i]<y[i])swap(x[i],y[i]);
		cout<<x[i];
		if(b[i]==1)cout<<"+"<<y[i]<<"="<<x[i]+y[i];
		if(b[i]==2)cout<<"-"<<y[i]<<"="<<x[i]-y[i];
		if(b[i]==3)cout<<"*"<<y[i]<<"="<<x[i]*y[i];
		if(b[i]==4)cout<<"/"<<y[i]<<"="<<x[i]/y[i];
		cout<<"\n";
	}
}
bool ck()
{
	for(int i=1;i<=4;i++)if(a[i]==24)return 1;
	return 0; 
}
void dfs(int t)
{
	if(t>3)
	{
		if(ck())
		{
			sc();
			exit(0);
		}
		return;
	}
	for(int i=2;i<=4;i++)
	{
		for(int j=1;j<=4;j++)
		{
			if(i!=j&&a[j]!=-1&&a[i]!=-1)
			{
				for(int k=1;k<=4;k++)
				{
					x[t]=a[i];
					y[t]=a[j];
					int l=a[i],r=a[j];
					if(k==1)
					{
						b[t]=1;
						a[i]=l+r;
					}
					if(k==2)
					{
						b[t]=2;
						a[i]=abs(l-r);
					}
					if(k==3)
					{
						b[t]=3;
						a[i]=l*r;
					}
					if(k==4)
					{
						if(a[j]==0||l%r!=0)continue;
						b[t]=4;
						a[i]=l/r;
					}
					a[j]=-1;
					dfs(t+1);
					a[i]=l;
					a[j]=r;
				}			
			}
		}
	}
}
int main()
{
	//freopen("Poker.in","r",stdin);
	//freopen("Poker.out","w",stdout);
	cin>>a[1]>>a[2]>>a[3]>>a[4];
	dfs(1); 
	cout<<"No answer!";
	return 0;
}