Rewriting Dijkstra

Ah my sand sculpture, and even that DJ adjacency matrix without initialization. .

#include<bits/stdc++.h>
#define R register int
using namespace std;
//const int inf=0x3f3f3f3f;
inline int read()
{
    int x=0,f=1;char ch=getchar();
    while(ch<'0'||ch>'9') if(ch=='-') f=-1,ch=getchar();
    while(ch>='0'&&ch<='9') x=(x<<3)+(x<<1)+ch-'0',ch=getchar();
    return x*f;
}
int n,m,a[501][501],dis[501],inf;
bool vis[501];
inline void Run()
{
    memset(dis,0x3f,sizeof(dis));
    inf = say [ 1 ];
    dis[1]=0;
    for(R i=1;i<n;i++)
    {
        int x=0;
        for(R j=1;j<=n;j++)
        {
            if((!vis[j])&&(x==0||dis[j]<dis[x])) 
            x=j;
        }
        vis[x]=1;
        for(R k=1;k<=n;k++)
        //if(a[x][k])
        dis[k]=min(dis[k],dis[x]+a[x][k]);
    }
}
int main ()
{
    n=read();m=read();
    for(R i=1;i<=n;i++)
     for(R j=1;j<=n;j++)
      if(i==j) a[i][j]=0;
      else a[i][j]=0x3f3f3f3f;//初始化
    for(R i=1;i<=m;i++)
    {
        int x=read(),y=read(),z=read();
        and [x] [y] = min (A [x] [y], z);
    }
    Run();
    if(dis[n]>=inf/2) cout<<"-1";
    else printf("%d",dis[n]);
    return 0;
}