leetcode-go/poj/3278.catch-that-cow/main.cc

#include <cstdio>
#include <cstring>
#include <queue>

using namespace std;

const int L = 200001;

bool set[L];

int main() {
  int N, K;
  while (scanf("%d %d", &N, &K) != EOF) {
    queue<int> q;
    q.push(N);
    memset(set, 0, sizeof(set));
    set[N] = true;
    int s = 1, t = 0;
    while (s != 0) {
      int n = q.front();
      q.pop();
      s--;
      if (n == K) break;
      if (n < K) {
        if (!set[2 * n]) {
          q.push(2 * n);
          set[2 * n] = true;
        }
        if (!set[n + 1]) {
          q.push(n + 1);
          set[n + 1] = true;
        }
      }
      if (0 < n && !set[n - 1]) {
        q.push(n - 1);
        set[n - 1] = true;
      }
      if (s == 0) {
        s = q.size();
        t++;
      }
    }
    printf("%d\n", t);
  }
  return 0;
}