Submission #75952824

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Source Code Expand

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int N, M;
    cin >> N >> M;

    vector<int> P(N + 1);
    for (int i = 1; i <= N; ++i) {
        cin >> P[i];
    }

    // adjacency list for edges with increasing elevation
    vector<vector<int>> adj(N + 1);
    for (int i = 0; i < M; ++i) {
        int u, v;
        cin >> u >> v;
        if (P[u] < P[v]) {
            adj[u].push_back(v);
        }
    }

    // sort nodes by elevation
    vector<int> order(N);
    for (int i = 0; i < N; ++i) order[i] = i + 1;
    sort(order.begin(), order.end(), [&](int a, int b) {
        return P[a] < P[b];
    });

    vector<int> dp(N + 1, -1);
    dp[1] = 1; // start node

    int ans = 1;
    for (int u : order) {
        if (dp[u] == -1) continue; // not reachable
        for (int v : adj[u]) {
            if (dp[v] < dp[u] + 1) {
                dp[v] = dp[u] + 1;
            }
        }
        if (dp[u] > ans) ans = dp[u];
    }

    cout << ans;
    return 0;
}

Submission Info

Judge Result