P3371 【模板】单源最短路径（弱化版）

P3371 【模板】单源最短路径（弱化版）

#include<bits/stdc++.h>
using namespace std;
const int maxn = 10005;
struct edge {
    int v, w;
};
vector<edge> maps[maxn];
int dis[maxn];
bool vis[maxn];
int n, m, s;
void add(int u, int v, int w) {
    maps[u].push_back(edge{v,w});
}
void spfa(int s) {
    for (int i = 1; i <= n; i++) {
        dis[i] = 2147483647;
        vis[i] = false;
    }
    queue<int> que;
    que.push(s), dis[s] = 0, vis[s] = true;
    while(!que.empty()) {
        int u = que.front();
        que.pop();
        vis[u] = false;
        for(int i = 0; i < maps[u].size(); i++) {
            int v = maps[u][i].v;
            int w = maps[u][i].w;
            if(dis[v] > dis[u]+w) {
                dis[v] = dis[u] + w;
                if(vis[v] == false) {
                    que.push(v);
                    vis[v] = true;
                }
            }
        }
    }
}
int main() {
    scanf("%d%d%d",&n,&m,&s);
    for(int i = 1; i <= m; i++) {
        int u, v, w; scanf("%d%d%d",&u,&v,&w);
        add(u,v,w);
    }
    spfa(s);
    printf("%d",dis[1]);
    for (int i = 2; i <= n; i++)
        printf(" %d",dis[i]);
    printf("\n");
    return 0;
}

 

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 10005, inf = 0x3f3f3f3f;
struct Edge {
    int from, to, dist;
};
struct HeapNode {
    int d, u;
    bool operator < (const HeapNode& rhs) const {
        return d > rhs.d;
    }
};
struct Dijkstra {
    int n, m;
    vector<Edge> edges;
    vector<int> G[maxn];
    bool done[maxn];
    int d[maxn];
    int p[maxn];

    void init(int n) {
        this->n = n;
        for (int i = 1; i <= n; i++) G[i].clear();
        edges.clear();
    }

    void AddEdge(int from, int to, int dist) {
        edges.push_back((Edge){from, to, dist});
        m = edges.size();
        G[from].push_back(m-1);
    }
    void dijkstra(int s) {
        priority_queue<HeapNode> Q;
        for (int i = 1; i <= n; i++) d[i] = inf;
        d[s] = 0;
        memset(done, 0, sizeof(done));
        Q.push((HeapNode){0, s});
        while (!Q.empty()) {
            HeapNode x = Q.top(); Q.pop();
            int u = x.u;
            if (done[u]) continue;
            done[u] = true;
            for (int i = 0; i < G[u].size(); i++) {
                Edge & e = edges[G[u][i]];
                if (d[e.to] > d[u] + e.dist) {
                    d[e.to] = d[u] + e.dist;
                    p[e.to] = G[u][i];
                    Q.push((HeapNode){d[e.to], e.to});
                }
            }
        }
    }
};
int main() {
    int n, m, s; scanf("%d%d%d",&n,&m,&s);
    Dijkstra dij;
    dij.init(n);
    for (int i = 1; i <= m; i++) {
        int u, v, w; scanf("%d%d%d",&u,&v,&w);
        dij.AddEdge(u,v,w);
    }
    dij.dijkstra(s);
    printf("%d",dij.d[1]==inf ? 2147483647 : dij.d[1]);
    for (int i = 2; i <= n; i++)
        printf(" %d",dij.d[i]==inf ? 2147483647 : dij.d[i]);
    printf("\n");
    return 0;
}