用queue写的广搜
#include<iostream>
#include<cstring>
#include<algorithm>
#include<queue>
using namespace std;
int N, K; //农夫和牛的位置
const int MAXN = 100000;
int visited[MAXN + 10];
struct Step
{
int x;
int steps;
Step(int xx, int s):x(xx),steps(s){}
};
int main()
{
while(cin >>N >>K)
{
queue <Step> q;
memset(visited, 0, sizeof(visited));
q.push(Step(N, 0));
visited[N] = 1;
while(!q.empty())
{
Step f = q.front();
if(f.x == K)
{
cout << f.steps<<endl;
break;
}
else
{
if(f.x-1 >= 0&&visited[f.x-1]==0)
{
q.push(Step(f.x-1,f.steps+1));
visited[f.x-1] = 1;
}
if(f.x+1 <= MAXN&&visited[f.x+1]==0)
{
q.push(Step(f.x+1,f.steps+1));
visited[f.x+1] = 1;
}
if(f.x*2 <= MAXN&&visited[f.x*2]==0)
{
q.push(Step(f.x*2,f.steps+1));
visited[f.x*2] = 1;
}
}
q.pop();
}
}
return 0;
}