题解 | 绕距

#include <cmath>
#include<bits/stdc++.h>
using namespace std;
int main() {
    int x1, y1;
    int x2,y2;
    cin>>x1>>y1;
    cin>>x2>>y2;
    int Δx,Δy;
   Δx=abs(x1-x2);
   Δy=abs(y1-y2);
   float dE,dM;
   dE=sqrt(Δx*Δx+Δy*Δy);
   dM=Δx+Δy;
   float Δ=abs(dE-dM);
   cout<<defaultfloat;
   cout<<fixed<<setprecision(6)<<Δ<<endl;
   return 0;
}