这题的代码我本想蹭个部分分，没想到过了

#include <bits/stdc++.h>
using namespace std;
int x,y,n,m;
int main(){
	cin>>x>>y>>n>>m;
	//y=kx+b,m=kn+b
	//y-m=k(x-n)
	double k=1.0*(y-m)/(x-n);
	double b=y-k*x;
	if(b==0)cout<<"y="<<k<<"x";
	else if(k==0.5){
		if(b==0.5)cout<<"y=1/2*x+1/2";
		else if(b==-0.5)cout<<"y=1/2*x-1/2";
		else cout<<"y=1/2*x+"<<b; 
	} 
	else if(k==-0.5){
		if(b==0.5)cout<<"y=-1/2*x+1/2";
		else if(b==-0.5)cout<<"y=-1/2*x-1/2";
		else cout<<"y=1/2*x-"<<b; 
	} 	
	else cout<<"y="<<k<<"x+"<<b;
    return 0;
}

结果就这么过了