P4779 【模板】单源最短路径

 

P4779 【模板】单源最短路径（标准版

#include <bits/stdc++.h>
using namespace std;
const int nn = 1e5 + 5;
const int mm = 2e5 + 5;
int d[nn],head[nn],ver[mm],edge[mm],nxt[mm],tot;
bool v[nn];
int n,m,s;
priority_queue<pair<int,int> >  que;

void add(int x,int y,int z){
    ver[++tot] = y;edge[tot] = z;//这条边的终点和边权
    nxt[tot] = head[x];head[x] = tot;//相当于指针
}
void dijstra(){
    memset(d,0x3f,sizeof(d));
    d[s] = 0;
    que.push(make_pair(0,s));

    while(!que.empty()){
        int x = que.top().second;//表示节点编号
        que.pop();
        if(v[x]) continue;
        v[x] = 1;
        //遍历所有出边
        for(int i = head[x];i;i=nxt[i]){
            int y = ver[i],z = edge[i];
            if(d[y] > d[x] + z){
                d[y] = d[x] + z;
                que.push(make_pair(-d[y],y));
            }
        }
    }
}
int main(){
    //freopen("in","r",stdin);
    ios::sync_with_stdio(0);
    cin >> n >> m >> s;
    while(m--){
        int x,y,w;
        cin >> x >> y >> w;
        add(x,y,w);
    }

    dijstra();
    for(int i = 1; i <= n; i++){
        if(i == 1) cout << d[i];
        else cout << " " << d[i];
    }
    return 0;
}