题解 | 绕距

#include <iostream>
#include <cmath>
using namespace std;
int main()
{
    int x1,y1,x2,y2;
    cin>>x1>>y1;
    cin>>x2>>y2;
    double d1,d2,d;
    d1=(abs(x1-x2)+abs(y1-y2));
    d2=sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
    d=abs(d1-d2);
    printf("%.18f",d);
    return 0;
}