HDU 2717 Catch That Cow（BFS）

#include <stdio.h>
#include <string.h>
int p[100001],o[100001];
int main()
{
int n,k,i,j,start=0,end=0,num=0;
while(scanf("%d%d",&n,&k)!=EOF)
{
memset(o,0,sizeof(o));
start=0,end=0,num=0;
p[start] = n;
o
= 1;
for(;;)
{
if(o[k]) break ;
num ++;
j = 1;
for(i = start; i <= end; i ++)
{
if(p[i]+1 <= 100000)
{
if(o[p[i]+1] == 0)
{
p[end+j] = p[i]+1;
o[p[i]+1] = 1;
j ++;
}
}
if(p[i]-1 >= 0)
{
if(o[p[i]-1] == 0)
{
p[end+j] = p[i]-1;
o[p[i]-1] = 1;
j ++;
}
}
if(p[i]*2 <= 100000)
{
if(o[p[i]*2] == 0)
{
p[end+j] = p[i]*2;
o[p[i]*2] = 1;
j ++;
}
}
}
start = end + 1;
end = end + j - 1;
}
printf("%d\n",num);
}
return 0;
}