Dijkstra 模板

#include <bits/stdc++.h>

using namespace std;
const int maxn = 150005;
const int maxm = 150005;
const int inf = 0x3f3f3f3f;
int n, m;
int head[maxn], ver[maxm], edge[maxm], Next[maxm], d[maxn], tot;
bool vis[maxn];
struct Node{
    int pos, val;
    bool operator > (const Node &tmp) const{
        return val > tmp.val;
    }
};
priority_queue<Node, vector<Node>, greater<Node> > pq;

void add(int x, int y, int z){
    ver[++ tot] = y, edge[tot] = z;
    Next[tot] = head[x], head[x] = tot;
}

void dijkstra(){
    memset(d, 0x3f, sizeof(d));
    memset(vis, 0, sizeof(vis));
    d[1] = 0;
    pq.push((Node){1, 0});
    while(pq.size()){
        Node now = pq.top();
        pq.pop();
        int x = now.pos;
        if(vis[x]) continue;
        vis[x] = 1;
        for(int i = head[x]; i; i = Next[i]){
            int y = ver[i], z = edge[i];
            if(vis[y]) continue;
            if(d[y] > d[x] + z){
                d[y] = d[x] + z;
                pq.push((Node){y, d[y]});
            }
        }
    }
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);

    cin >> n >> m;
    for(int i = 1; i <= m; ++ i){
        int x, y, z;
        cin >> x >> y >> z;
        add(x, y, z);
    }
    dijkstra();

    if(d[n] == inf) cout << -1 << endl;
    else cout << d[n] << endl;
    return 0;
}