Submission #831156

#	Time	Username	Problem	Language	Result	Execution time	Memory
831156		PurpleCrayon	Sky Walking (IOI19_walk)	C++17	10 / 100	30 ms	17000 KiB

walk

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

#define sz(v) int(v.size())
#define ar array
typedef long long ll;
const int N = 2e5+10;
const ll INF = 1e18+10;

template <class T>
using min_pq = priority_queue<T, vector<T>, greater<T>>;

int n, m;
vector<pair<int, int>> adj[N];
ll dist[N];

void add_edge(int a, int b, int w) {
    assert(w >= 0);
	adj[a].emplace_back(b, w);
	adj[b].emplace_back(a, w);
}

void dijkstra(int S) {
	fill(dist, dist + N, INF);

	min_pq<pair<ll, int>> pq;
	pq.push({dist[S] = 0, S});

	while (!pq.empty()) {
		auto [d_c, c] = pq.top(); pq.pop();
		if (dist[c] != d_c) continue;
		for (auto [nxt, w] : adj[c]) {
			if (dist[nxt] > dist[c] + w) {
				dist[nxt] = dist[c] + w;
				pq.push({dist[nxt], nxt});
			}
		}
	}
}

long long min_distance(vector<int> x, vector<int> h, vector<int> l, vector<int> r, vector<int> y, int s, int g) {
	n = sz(x), m = sz(l);
    for (int i = 0; i < m; i++) {
        for (int j = l[i]; j <= r[i]; j++) {
            // i * n + j
            if (j > l[i]) {
                add_edge(i * n + j - 1, i * n + j, x[j] - x[j-1]);
            }
        }
    }

    for (int j = 0; j < n; j++) {
        vector<int> open;
        for (int i = 0; i < m; i++) if (l[i] <= j && j <= r[i] && y[i] <= h[j]) {
            open.push_back(i);
        }
        sort(open.begin(), open.end(), [&](int a, int b) { return y[a] < y[b]; });

        int p = -1;
        for (int i : open) {
            if (p != -1) {
                add_edge(i * n + j, p * n + j, y[i] - y[p]);
            }

            p = i;
        }
    }

    int S = n * m;
    for (int i = 0; i < m; i++) {
        if (l[i] <= s && s <= r[i] && y[i] <= h[s]) {
            add_edge(S, i * n + s, y[i]);
        }
    }

    dijkstra(S);

    ll ans = INF;
    for (int i = 0; i < m; i++) {
        if (l[i] <= g && g <= r[i] && y[i] <= h[g]) {
            ans = min(ans, dist[i * n + g] + y[i]);
        }
    }

    return (ans == INF ? -1 : ans);
}

• Subtask 1: 10 / 10
• Subtask 2: 0 / 14
• Subtask 3: 0 / 15
• Subtask 4: 0 / 18
• Subtask 5: 0 / 43