c++怎么实现迪杰斯特拉(Dijkstra)算法_c++最短路径算法实现步骤

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

void dijkstra(vector<vector<pair<int, int>>>& adj, int start) {
    int n = adj.size();
    vector<int> dist(n, INT_MAX);
    vector<bool> visited(n, false);
    
    // 起点距离为0
    dist[start] = 0;
    
    // 优先队列：{距离, 顶点}
    priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;
    pq.push({0, start});
    
    while (!pq.empty()) {
        int u = pq.top().second;
        pq.pop();
        
        if (visited[u]) continue;
        visited[u] = true;
        
        // 遍历所有邻居
        for (auto& edge : adj[u]) {
            int v = edge.first;
            int weight = edge.second;
            
            if (!visited[v] && dist[u] + weight < dist[v]) {
                dist[v] = dist[u] + weight;
                pq.push({dist[v], v});
            }
        }
    }
    
    // 输出结果
    for (int i = 0; i < n; ++i) {
        cout << "从起点到" << i << "的最短距离: ";
        if (dist[i] == INT_MAX)
            cout << "不可达" << endl;
        else
            cout << dist[i] << endl;
    }
}

int main() {
    int n = 5;
    vector<vector<pair<int, int>>> adj(n);
    
    // 添加边：u -> v，权重 w
    adj[0].push_back({1, 10});
    adj[0].push_back({3, 5});
    adj[1].push_back({2, 1});
    adj[1].push_back({3, 2});
    adj[2].push_back({4, 4});
    adj[3].push_back({1, 3});
    adj[3].push_back({2, 9});
    adj[3].push_back({4, 2});
    adj[4].push_back({0, 7});
    adj[4].push_back({2, 6});
    
    dijkstra(adj, 0);
    
    return 0;
}