按照常识，距离越远则选择骑车，看看临界值是什么情况:

$\frac n {1.2} = \frac n {3.0} + 50$ 解得 $n = 100$

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

int main(){
    int n; cin >> n;
    if(n < 100) cout << "Walk";
    if(n > 100) cout << "Bike";
    if(n == 100) cout << "All";
	return 0;
}