Catch That Cow(POJ3278)(入门)

どこでもドア：http://poj.org/problem?id=3278

AC CODE:

#include<iostream>#include<cstdio>#include<algorithm>#include<cmath>#include<cstring>#include<string>#include<sstream>#include<set>#include<cstdlib>#include<map>#include<queue>using namespace std;typedef long long LL;const int M= 100000+10;int n,m,ans[M],vis[M];int main(){    int n,m;    cin>>n>>m;    int x;    queue<int>que;    que.push(n);    ans[n] = 0;        while(!que.empty())        {            x = que.front();            que.pop();            vis[x] = 1;            if (x==m)            {                cout<<ans[x]<<endl;                break;            }            if (x-1>=0 && vis[x-1]==0)            {                que.push(x-1);                ans[x-1] = ans[x] + 1;                vis[x-1] = 1;            }            if (x+1<100001 && vis[x+1]==0)            {                que.push(x+1);                ans[x+1] = ans[x] + 1;                vis[x+1] = 1;            }            if (x*2<100001 && vis[x*2]==0)//这里判断,&&前后判断颠倒位置(写成vis[x*2]==0&&x*2<100001)就会re，这样就ac。。原因待解。。            {                que.push(x*2);                ans[x*2] = ans[x] + 1;                vis[x*2] = 1;            }        }    return 0;}