洛谷

https://www.luogu.org/problemnew/show/P1426

题目说的是小鱼进入探测器一秒后就会有危险，所以不应该让小鱼先游，而是先检测探测器。

#include<bits/stdc++.h>
using namespace std;
#define ll long long

int s,x;

int main(){
    scanf("%d%d",&s,&x);
    double l=s-x;
    //cout<<l<<endl;
    double r=s+x;
    double cur=0;
    double dx=7.0;
    int maxt=5000;
    while(maxt--){
        if(cur>=l-1e-8)
            break;
        cur+=dx;
        dx*=0.98;
    }

    cur+=dx;
    dx*=0.98;
    if(cur>=r+1e-8)
        printf("n
");
    else
        printf("y
");
}