HDU 2717 Catch That Cow（BFS）

题目链接

好裸，BFS。杭电多组。。2A。。

#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[n] = 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;
}