题解 | 绕距

#include <iostream>
#include <cmath>
#include <iomanip>
using namespace std;
int main(){
    int x1,y1,x2,y2;
    cin>>x1>>y1>>x2>>y2;
    double de,dm,delta;
    de=sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
    dm=abs(x1-x2)+abs(y1-y2);
    delta=fabs(dm-de);
    cout<<fixed<<setprecision(15)<<delta;     //获取更高精度
    return 0;
}