Submission #991328

#	Time	Username	Problem	Language	Result	Execution time	Memory
991328		BF001	Mobile (BOI12_mobile)	C++17	12 / 100	228 ms	8276 KiB

mobile

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

#define N 1000005
#define ld double

int n, x[N], y[N], len;

signed main(){
    ios_base::sync_with_stdio(0);
    cin.tie(NULL);
    
    cin >> n >> len;
    for (int i = 1; i <= n; i++) cin >> x[i] >> y[i];

    ld l = 1, r = 1.5e9;
    while (r - l > 1e-3){
    	ld mid = (l + r) / 2.0;
    	ld cur = 0;
    	for (int i = 1; i <= n; i++){
    		ld denta = sqrt(mid * mid - y[i] * y[i]);
    		ld a = x[i] - denta;
    		ld b = x[i] + denta;
    		if (a <= cur) cur = max(cur, b);
    	}
    	if (cur >= len) r = mid;
    	else l = mid;
    }

    cout << fixed << setprecision(4) << l;
    
    return 0;
}     

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