dijkstra+堆优化

模板

// luogu-judger-enable-o2
// magic bag of tricks 
// 洛谷评测机，你别无选择 
#include <iostream>
#include <cstring>
#include <queue>
#include <cstdio>
#include <algorithm>
using namespace std;
const int maxn = 500000 + 100;
const int inf = 2147483647;
int n,m,k;
struct edge
{
    int u,v,w;
    int next;
}e[maxn];
int head[maxn],tot;
struct node
{
    int x,val;
    bool operator < (node a) const 
    {
        return val>a.val;
    }
};
priority_queue<node>q;
void add(int u,int v,int w)
{
    e[++tot] = (edge){u,v,w,head[u]};
    head[u] = tot;
}
int vis[maxn],dis[maxn];
void dijkstra(int x)
{
    memset(vis,0,sizeof(vis));
    for(int i=1;i<=n;i++) dis[i] = inf;
    dis[x]=0;
    q.push((node){x,0});
    while(!q.empty())
    {
        int k = q.top().x;
        q.pop();
        if(vis[k]) continue;
        vis[k] = 1;
        for(int i = head[k]; i; i = e[i].next) 
        {
            int v = e[i].v;
            if(dis[v] > dis[k] + e[i].w) 
            {
                dis[v] = dis[k] + e[i].w;
                q.push((node){v,dis[v]});
    }
   }
 }
}
int main()
{
    ios::sync_with_stdio(false);
    cin>>n>>m>>k;
    for(int i=1;i<=m;i++)
    {
        ios::sync_with_stdio(false);
        int u,v,w;
        cin>>u>>v>>w;
        add(u,v,w);
    }
    dijkstra(k);
    for(int i=1;i<=n;i++)
    cout<<dis[i]<<" ";
}