POJ 3278

// 百度空间太 2B 了。一点儿都不好用，垃圾。

 

// 非 STL 版。

// (C++)            AC     916K    16MS   (C:编译错误)
// (G++ / Gcc)  AC    1104K    16MS

#include <stdio.h>

int main() {
    int visited[100001] = {0};
    int queue[100001] = {0};
    int qBegin = 0, qEnd = 0;
    int N, K;
    scanf("%d %d", &N, &K);
   
    if (N == K) {
        puts("0");
        return 0;
    }

    visited[N] = 1;
    queue[qEnd++] = N;

    for (int i = 1; N != K; ++i) { //
        int layer = qEnd;
        while (qBegin < layer) {
          
            N = queue[qBegin++];
           
            if (N > 0 && !visited[N - 1]) {
                visited[N - 1] = 1;
                if (N - 1 == K) { printf("%d\n", i); return 0; }
                queue[qEnd++] = N - 1;
            }
            if (N < 100000 && !visited[N + 1]) {
                visited[N + 1] = 1;
                if (N + 1 == K) { printf("%d\n", i); return 0; }
                queue[qEnd++] = N + 1;
            }
            if (2 * N <= 100000 && !visited[2 * N]) {
                visited[2 * N] = 1;
                if (2 * N == K) { printf("%d\n", i); return 0; }
                queue[qEnd++] = 2 * N;
            }
        }
    }

    return 0;
}