POJ 3278 Catch That Cow

　　一维的广搜，从当前点到下个点有三种选择，然后求步数即可。用了STL的队列，

然后忘了加using namespace std,检查浪费了时间。

 

/*Accepted 860K 110MS C++ 640B 2012-05-26 20:44:59 */
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<queue>
using namespace std;
#define MAXN 100005
int d[MAXN], N, K;

void bfs()
{
    queue<int> q;
    memset( d, -1, sizeof d);
    d[N] = 0;
    q.push(N);
    while( !q.empty())
    {
        int x = q.front(); q.pop();
        if( x == K) break;
        int nx[3];
        nx[0] = x * 2; nx[1] = x - 1; nx[2] = x + 1;
        for( int i = 0; i < 3; i ++)
        {
            if( nx[i] >= 0 && nx[i] <= 100000 && d[nx[i]] < 0) {
                d[nx[i]] = d[x] + 1;
                q.push(nx[i]);
            }
        }
    }
}

int main()
{
    while( scanf( "%d%d", &N, &K) == 2)
    {
        bfs();
        printf( "%d\n", d[K]);
    }
    return 0;
}