题解 | 绕距

#include <iomanip>
#include <iostream>
#include<cmath>
using namespace std;

int main() {
  int x1,x2,y1,y2;
  double dE,dM,d;
  cin>>x1>>y1;
  cin>>x2>>y2;
  dE = sqrt(pow(x1-x2, 2) + pow(y1-y2, 2));
  dM=abs(x1-x2)+abs(y1-y2);
  d=fabs(dM-dE);
  cout<<fixed<<setprecision(10)<<d;
}