游戏关卡(Game Levels) 题解

思路分析

按题目要求使用对应数据结构与算法模拟/递推求解，注意数据范围边界与时间复杂度。

参考代码

#include <iostream>
#include <vector>
#include <queue>
#include <functional>
using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n;
    if (!(cin >> n)) return 0;
    vector<vector<pair<int, long long>>> adj(n + 1);
    for (int i = 1; i <= n - 1; ++i) {
        long long a, b;
        int x;
        cin >> a >> b >> x;
        adj[i].push_back({i + 1, a});
        adj[i].push_back({x, b});
    }
    const long long INF = (1LL << 60);
    vector<long long> dist(n + 1, INF);
    priority_queue<pair<long long, int>, vector<pair<long long, int>>, greater<pair<long long, int>>> pq;
    dist[1] = 0;
    pq.push({0, 1});
    while (!pq.empty()) {
        auto top = pq.top();
        pq.pop();
        long long d = top.first;
        int u = top.second;
        if (d > dist[u]) continue;
        for (auto& edge : adj[u]) {
            int v = edge.first;
            long long w = edge.second;
            if (dist[u] + w < dist[v]) {
                dist[v] = dist[u] + w;
                pq.push({dist[v], v});
            }
        }
    }
    cout << dist[n] << "\n";
    return 0;
}