Submission #1002017

#	Time	Username	Problem	Language	Result	Execution time	Memory
1002017		coolboy19521	Watching (JOI13_watching)	C++17	100 / 100	623 ms	64832 KiB

watching

#pragma GCC optimize("Ofast")
#include"bits/stdc++.h"
 
#define int long long
 
using namespace std;
 
const int sz = 2e3 + 20;
const int inf = 1e18;
 
vector<vector<int>> aj[sz];
int nw[sz], nww[sz];
int n, p, q;
int vi[sz][sz];
int vs[sz][sz];
int a[sz];
bool f;
 
void dfs(int v, int cl, int cr) {
    vi[v][cl]=min(vi[v][cl], cr);
    vs[v][cr]=min(vs[v][cr], cl);
    if (cl > p || cr > q) return;
    if (v == n + 1) {
        f |= (cl <= p && cr <= q);
    } else {
        for (auto& u : aj[v]) {
            if(cr+u[2]>=vi[u[0]][cl+u[1]] || cl+u[1]>=vs[u[0]][cr+u[2]]) continue;
            if(u[1] <= nw[v] || u[2] <= nww[v]) {
                dfs(u[0], cl + u[1], cr + u[2]);
            }
            if (f) return;
        }
    }
}
 
bool che(int mi) {
    // map<vector<int>,bool>vi;
    for (int i = 1; i <= n; i ++) {
        aj[i].clear();
        int d = lower_bound(a + 1, a + n + 1, a[i] + mi) - &a[i];
        int c = lower_bound(a + 1, a + n + 1, a[i] + 2 * mi) - &a[i];
        aj[i].push_back({i + d, 1, 0});
        aj[i].push_back({i + c, 0, 1});
        nw[i] = nww[i] = inf;
    }
    fill_n(&vi[0][0], sz * sz, INT_MAX);
    fill_n(&vs[0][0], sz * sz, INT_MAX);
    f = false;
    dfs(1, 0, 0);
    return f;
}
 
signed main() {
    cin.tie(nullptr)->sync_with_stdio(false);
 
    cin >> n >> p >> q;
 
    for (int i = 1; i <= n; i ++) {
        cin >> a[i];
    }
 
    sort(a + 1, a + n + 1);
    a[n + 1] = inf;

    int le, ri;
    le = 0, ri = (a[n] - a[1]) / (p + q) + 10;
    // cout << ri << '\n';
 
    while (1 < ri - le) {
        int mi = le + (ri - le) / 2;
 
        if (che(mi)) {
            ri = mi;
        } else {
            le = mi;
        }
    }
 
    cout << ri << '\n';
}

• Subtask 1: 50 / 50
• Subtask 2: 50 / 50