Catch That Cow

think:
1广度优先搜索（队列思想）
2以结构数组为基础的队列思想
3反思:自己因为vis数组有的初始化位置不对，导致runtime error.???

hint;
一个农夫的奶牛跑了，他要追上奶牛，奶牛不动，他和奶牛在同一坐标轴上，他可以有3种移动情况，1>他可以向前移动1格2>他可以向后移动1格3>他可以移动目前格数的两倍，三种移动方式花费的时间相同，求最少时间

poj原题链接

Catch That Cow
Time Limit: 2000MS Memory Limit: 65536KB

Problem Description
Farmer John has been informed of the location of a fugitive cow and wants to catch her immediately. He starts at a point N (0 ≤ N ≤ 100,000) on a number line and the cow is at a point K (0 ≤ K ≤ 100,000) on the same number line. Farmer John has two modes of transportation: walking and teleporting. * Walking: FJ can move from any point X to the points X - 1 or X + 1 in a single minute * Teleporting: FJ can move from any point X to the point 2 × X in a single minute. If the cow, unaware of its pursuit, does not move at all, how long does it take for Farmer John to retrieve it?

Input
Line 1: Two space-separated integers: N and K

Output
Line 1: The least amount of time, in minutes, it takes for Farmer John to catch the fugitive cow.

Example Input
5 17

Example Output
4

Hint
poj3278 有链接提示的题目请先去链接处提交程序，AC后提交到SDUTOJ中，以便查询存档。
The fastest way for Farmer John to reach the fugitive cow is to move along the following path: 5-10-9-18-17, which takes 4 minutes.
Author

以下为accepted代码

#include <stdio.h>#include <string.h>struct node{    int Data;    int size;}link[200000], ans, t;int tp, op, vis[200000];void BFS(int N, int K){    link[tp].Data = N;    link[tp].size = 0;    tp++;    vis[N] = 1;    while(op < tp)    {        ans = link[op++];        if(ans.Data == K)        {            printf("%d\n", ans.size);            return;        }        if(vis[ans.Data+1] == 0 && ans.Data <= K)        {            link[tp].Data = ans.Data + 1;            link[tp].size = ans.size + 1;            //vis[ans.Data] = 1;            vis[link[tp].Data] = 1;            tp++;        }        if(vis[ans.Data-1] == 0 && ans.Data > 0)        {            link[tp].Data = ans.Data - 1;            link[tp].size = ans.size + 1;            //vis[ans.Data] = 1;            vis[link[tp].Data] = 1;            tp++;        }        if(vis[(ans.Data)*2] == 0 && ans.Data <= K)        {            link[tp].Data = (ans.Data)*2;            link[tp].size = ans.size + 1;            //vis[ans.Data] = 1;            vis[link[tp].Data] = 1;            tp++;        }    }}int main(){    int N, K;    while(scanf("%d %d", &N, &K) != EOF)    {        tp = op = 0;        memset(vis, 0, sizeof(vis));        BFS(N, K);    }    return 0;}/***************************************************User name: Result: AcceptedTake time: 0msTake Memory: 1896KBSubmit time: 2017-02-16 20:23:14****************************************************/

以下为runtime error代码

#include <stdio.h>#include <string.h>struct node{    int Data;    int size;}link[200000], ans, t;int tp, op, vis[200000];void BFS(int N, int K){    link[tp].Data = N;    link[tp].size = 0;    tp++;    vis[N] = 1;    while(op < tp)    {        ans = link[op++];        if(ans.Data == K)        {            printf("%d\n", ans.size);            return;        }        if(vis[ans.Data+1] == 0 && ans.Data <= K)        {            link[tp].Data = ans.Data + 1;            link[tp].size = ans.size + 1;            vis[ans.Data] = 1;            //vis[link[tp].Data] = 1;            tp++;        }        if(vis[ans.Data-1] == 0 && ans.Data > 0)        {            link[tp].Data = ans.Data - 1;            link[tp].size = ans.size + 1;            vis[ans.Data] = 1;            //vis[link[tp].Data] = 1;            tp++;        }        if(vis[(ans.Data)*2] == 0 && ans.Data <= K)        {            link[tp].Data = (ans.Data)*2;            link[tp].size = ans.size + 1;            vis[ans.Data] = 1;            //vis[link[tp].Data] = 1;            tp++;        }    }}int main(){    int N, K;    while(scanf("%d %d", &N, &K) != EOF)    {        tp = op = 0;        memset(vis, 0, sizeof(vis));        BFS(N, K);    }    return 0;}/***************************************************User name: Result: Runtime ErrorTake time: 0msTake Memory: 0KBSubmit time: 2017-02-16 20:22:20****************************************************/