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news 2026/5/31 17:34:28

11.17

这场又是神人模拟赛。

大分题面。

t1

题意比Fwb模糊不清+inf。

赛后统计小样例2大家一共读出了6种答案。

感觉就是描述不清的detect。

读懂后纯简单题。

但有一车细节。

挂细节上了(代码中感叹号处)。

code

#include <bits/stdc++.h>
#define pir pair<int, int>
#define ldb long double
#define fi first
#define se second
using namespace std;
const int N = 1e5 + 10;
const ldb eps = 1e-10;
int h, n;
pir a[N];
priority_queue<int> q;inline int cmp(ldb a, ldb b)
{if (a - b > eps)return 1;if (b - a > eps)return -1;return 0;
}signed main()
{freopen("water.in", "r", stdin);freopen("water.out", "w", stdout);// ios::sync_with_stdio(0);// cin.tie(0);scanf("%d%d", &h, &n);bool f = 0;for (int i = 1; i <= n; ++i){scanf("%d%d", &a[i].fi, &a[i].se); // t hif (!a[i].se)f = 1;}if (!f){cout << -1;return 0;}sort(a + 1, a + 1 + n);ldb ans = 0, res = h;for (int i = 1; i <= n; ++i){// cerr << "i=" << i << "\n";// printf("i=%d\n", i);ldb lim = a[i].fi - a[i - 1].fi;if (!q.size()){ans += lim;if (cmp(a[i].se, res) != 1) // a<=bq.push(a[i].se);// printf("res=%.6Lf ans=%.6Lf\n", res, ans);continue;}while (q.size()){ldb x = q.top();if (cmp(x, res) != -1){// cout << "-----------------------------\n";// cout << "x=" << x << " res=" << res << "\n";// cout << "-----------------------------\n";q.pop();continue;}// cerr << "x=" << x << "\n";ldb tim = (res - x) / (ldb)q.size();// printf("tim=%.6Lf x=%Lf lim=%Lf\n", tim, x, lim);if (cmp(tim, lim) == 1){ans += lim, res -= lim * (ldb)q.size();lim = 0; //!!!!!!!!!!!!!!!!!!!!!!!break;}else{ans += tim, res = x;q.pop();lim -= tim;}// printf("ans=%.6Lf\n", ans);}if (cmp(res, 0) != 1)break;ans += lim; //!!!!!!!!!!!!!!!!!!!!!// printf("ans=%.6Lf\n", ans);// printf("siz=%d res=%.6Lf ans=%.6Lf\n", (int)q.size(), res, ans);if (cmp(a[i].se, res) != 1)q.push(a[i].se);}// printf("res=%.6Lf ans=%.6Lf\n", res, ans);// cerr << "!\n";while (q.size()){if (cmp(res, 0) != 1)break;ldb x = q.top();ans += (ldb)(res - x) / (ldb)q.size();res = x;q.pop();}printf("%.6Lf", ans);return 0;
}/*
detect
*/