【luogu P3371 单源最短路径】 模板 dij + heap

题目链接：https://www.luogu.org/problemnew/show/P3371#sub

堆优化迪杰斯特拉，留着以后复习用

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <queue>
using namespace std;
const int inf = 2147483647;
const int maxn = 500001;
struct Edge{
    int u,v,w;
}e[maxn];
struct Point{
    int na,s;
}dis[maxn];
struct cmp{
    bool operator ()(Point &a,Point &b){
        return a.s>b.s;
    }
};
priority_queue<Point,vector<Point>,cmp> q;
int m, n, sta;
int head[maxn];
bool vis[maxn];
int main()
{
    scanf("%d%d%d",&n,&m,&sta);//n 点  m 边 
    for(int i = 1; i <= m; i++)
    {
        int x,y,z;
        scanf("%d%d%d",&x,&y,&z);
        e[i].u = y;
        e[i].v = head[x];
        e[i].w = z;
        head[x] = i;    
    } 
    
    for(int i = 1; i <= n; i++)
    {
        dis[i].na = i;
        dis[i].s = inf;
    }
    
    dis[sta].s = 0;
    int now = 0;
    vis[0] = 1;
    q.push(dis[sta]);
    
    for(int k = 1; k < n; k++)
    {
        while(vis[now])
        {
            now = q.top().na;
            q.pop();
        }
        vis[now] = 1;
        int c = head[now];
        while(c)
        {
            int mu = e[c].u;
            if(dis[mu].s > dis[now].s+e[c].w)
            {
                dis[mu].s = dis[now].s+e[c].w;
                q.push(dis[mu]);
            }
            c = e[c].v;            
        }
    }
    for(int i = 1; i <= n; i++)
    printf("%d ",dis[i].s);
    return 0; 
}