Codeforces Round #420 (Div. 2), problem: (D) Okabe and City Solution In C/C++

#include<iostream>
#include<cstdio>
#include<cstring>
#include<queue>
#include<cmath>
using namespace std;
const int maxn=1e4+5;
const int inf=0x7f7f7f7f;
int x[maxn],y[maxn],dis[maxn];
bool vis[maxn];
int k,n,m;
int bfs()
{
queue<int>q;
q.push(1);
//memset
//for(int i=1;i<=n;i++)dis[i]=inf;
memset(dis,0x7f,sizeof dis);
dis[1]=0;
vis[1]=true;
while(!q.empty())
{
int u;
u=q.front();q.pop();
for(int i=1;i<=k;i++)
{
if(u==i)continue;
int w=inf;
int l1=abs(x[i]-x[u]);
int l2=abs(y[i]-y[u]);
if(l1+l2<=1)w=0;
else if(l1<=2||l2<=2)w=1;
if(dis[i]>dis[u]+w)
{
dis[i]=dis[u]+w;
if(!vis[i])
{
vis[i]=true;q.push(i);
}
q.push(i);
}
}
vis[u]=0;

}
return dis[k]==inf?-1:dis[k];

}
int main()
{
scanf(“%d %d %d”,&n,&m,&k);
bool flag=false;
for(int i=1;i<=k;i++)
{
scanf(“%d %d”,&x[i],&y[i]);
flag|=(x[i]==n&&y[i]==m);
}
if(!flag)
{
x[++k]=n+1;y[k]=m+1;
}
printf(“%d\n”,bfs());
}