自己写的Dijkstra模板

Posted 2020-06-29 very_czy

话不多说，邻接表+队列优化。

#include <cstdio>
#include <iostream>
#include <cmath>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <queue>

using namespace std;

const int INF=0x3f3f3f3f;
const int MAXN=1000010;
const int MAXE=1000010;

struct qnode
{
    int v;
    int c;
    qnode(int _v=0,int _c=0):v(_v),c(_c){}
    bool operator <(const qnode &r)const
    {
        return c>r.c;
    }
};

struct Edge
{
    int v,cost;
    int next;
};

Edge edge[MAXE];
int head[MAXN];
bool vis[MAXN];
int dist[MAXN];
int tot;
int n,m;
priority_queue<qnode>que;

void Dijkstra(int start,int n)//点的编号从1开始
{
    dist[start]=0;
    que.push(qnode(start,0));
    qnode tmp;
    while(!que.empty())
    {
        tmp=que.top();
        que.pop();
        int u=tmp.v;
        if(vis[u])continue;
        vis[u]=true;
        for(int i=head[u];i!=-1;i=edge[i].next)
        {
            int v=edge[i].v;
            int cost=edge[i].cost;
            if(!vis[v]&&dist[v]>dist[u]+cost)
            {
                dist[v]=dist[u]+cost;
                que.push(qnode(v,dist[v]));
            }
        }
    }
}

void addedge(int u,int v,int w)
{
    edge[tot].v=v;
    edge[tot].cost=w;
    edge[tot].next=head[u];
    head[u]=tot;
    tot++;
}

void init()
{
    tot=0;
    memset(edge,0,sizeof(edge));
    memset(head,-1,sizeof(head));
    memset(vis,false,sizeof(vis));
    for(int i=1;i<=n;i++)dist[i]=INF;
    while(!que.empty())que.pop();
}

int main()
{
//    freopen("in.txt","r",stdin);
//    freopen("out.txt","w",stdout);
    int T;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%d%d",&n,&m);
        init();
        for(int i=0;i<m;i++){
            int from,to,cost;
            scanf("%d%d%d",&from,&to,&cost);
            addedge(from,to,cost);
        }
        Dijkstra(1,n);//答案在dist数组中
    }
    return 0;
}