最短路径spfa

#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <queue>
using namespace std;

const int inf = 1<<30;
const int L = 200000;

struct Edges
{
    int x,y,w,next;
} e[L<<2];

int head[L];
int dis[L];
int vis[L];
int cnt[L];

void AddEdge(int x,int y,int w,int k)
{
    e[k].x = x,e[k].y = y,e[k].w = w,e[k].next = head[x],head[x] = k;
}
int relax(int u,int v,int c)
{
    if(dis[v]>dis[u]+c)
    {
        dis[v] = dis[u]+c;
        return 1;
    }
    return 0;
}

int SPFA(int src)
{
    int i;
    memset(cnt,0,sizeof(cnt));
    dis[src] = 0;
    queue<int> Q;
    Q.push(src);
    vis[src] = 1;
    cnt[src]++;
    while(!Q.empty())
    {
        int u,v;
        u = Q.front();
        Q.pop();
        vis[u] = 0;
        for(i = head[u]; i!=-1; i=e[i].next)
        {
            v = e[i].y;
            if(relax(u,v,e[i].w)==1 && !vis[v])
            {
                Q.push(v);
                vis[v] = 1;
            }
        }
    }
}

int main()
{
    int t,n,m;
    int i,j;
    scanf("%d%d",&n,&m);
    memset(e,-1,sizeof(e));
    for(i = 1; i<=n; i++)
    {
        dis[i] = inf;
        vis[i] = 0;
        head[i] = -1;
    }
    for(i = 0; i<m; i++)
    {
        int x,y,w;
        scanf("%d%d%d",&x,&y,&w);
        AddEdge(x,y,w,i);
    }
    SPFA(1);
    for(i = 2; i<=n; i++)
        printf("%d\n",dis[i]);


    return 0;
}










#include<iostream>
#include<queue>
#include<memory.h>
using namespace std;

const int inf=1<<30;
const int N=200005;
struct Edge
{
	int u,v,w,next;
};
int head[N];
int dis[N];
int vis[N];
Edge e[N];

void addEdge(int from,int to,int we,int i)
{
	e[i].u=from;
	e[i].v=to;
	e[i].w=we;
	e[i].next=head[from];
	head[from]=i;
}

bool releax(int u,int v,int w)
{
	if(dis[u]+w<dis[v])
	{
		dis[v]=dis[u]+w;
		return true;
	}
	return false;
}


void spfa(int x)
{
	queue<int> q;
	q.push(x);
	vis[x]=1;
	dis[x]=0;
	while(!q.empty())
	{
		int u,v,i;
		u=q.front();
		q.pop();
		vis[u]=0;
		for(i=head[u];i!=-1;i=e[i].next)
		{
			v=e[i].v;
			if(!vis[v]&&releax(u,v,e[i].w))
			{
				q.push(v);
				vis[v]=1;
			}
		}
	}
	
}







int main()
{
	//cout<<inf<<' '<<N<<endl;
	int n,m,i,u,v,w;
	//memset(head,-1,sizeof(head));
	//memset(dis,inf,sizeof(dis));
	//memset(vis,0,sizeof(vis));
	//memset(e,-1,sizeof(e));
	cin>>n>>m;
	for(i=1;i<=n;i++)
	{
		head[i]=-1;
		dis[i]=inf;
		vis[i]=0;
	} 
	for(i=1;i<=m;i++)
	{
		cin>>u>>v>>w;
		addEdge(u,v,w,i); 
	}
	
	/*for(i=1;i<=m;i++)
	{
		cout<<e[i].u<<' '<<e[i].v<<' '<<e[i].next<<endl;
	}
	for(i=1;i<=3;i++)
	cout<<head[i]<<' ';*/
	spfa(1);
	for(i=2;i<=n;i++)
	{
		cout<<dis[i]<<endl;
	}
	
	
	
	
	return 0;
}