POJ-3278 Catch That Cow bfs

跟杭电的奇怪的楼梯非常想。

代码如下：

#include <cstdio>

#include <queue>

using namespace std;



struct Node

{

    int x, t;

}e[100005], pos;



int N, K, front, tail, hash[100005];



void getnewpos(int x, int a[])

{

    a[0] = x - 1;

    a[1] = x + 1;

    a[2] = x << 1;    

}



int bfs()

{ 

    memset(hash, 0, sizeof (hash));

    hash[N] = 1;

    int x[3];

    front = 0, tail = 1;

    e[tail].x = N, e[tail].t = 0;

    while (front != tail) {

        pos = e[++front];

        getnewpos(pos.x, x);

        for (int i = 0; i < 3; ++i) {

            if (!hash[x[i]] && x[i] >= 0 && x[i] <= 100000) {

                hash[x[i]] = 1;

                if (x[i] == K) {

                    return pos.t + 1;

                }

                else {

                    ++tail;

                    e[tail].x = x[i];

                    e[tail].t = pos.t + 1;

                }

            }

        }

    }

}



int main()

{

    while (scanf("%d %d", &N, &K) == 2) {

        printf("%d\n", bfs());

    }

}