NOI OpenJudge 2971:抓住那头牛 BFS

#include <iostream>
#include <cstdio>
#include <cstring>
#include <queue>
using namespace std;

int N, K;
bool vis[100010 << 1];
struct T{
int num, cost;//zb,dis
};

queue <T> q;
int bfs(int x)
{
q.push((T){x,0});
vis[x] = 1;
while(q.size())
{
T x = q.front();
q.pop();
if(x.num < 0)//|| (vis[x.num] && x.num != N))
continue;
if(x.num == K)
return x.cost;
if(x.num + 1 < (100010 << 1) && !vis[x.num + 1])
q.push((T){x.num+1,x.cost+1}),vis[x.num + 1] = true;
if(x.num - 1 >= 0 && !vis[x.num - 1])
q.push((T){x.num-1,x.cost+1}),vis[x.num - 1] = true;
if(x.num * 2 < (100010 << 1) && !vis[x.num * 2])
q.push((T){x.num*2,x.cost+1}),vis[x.num * 2] = true;
}
return 1/0;
}

int main()
{
cin >> N >> K;
cout << bfs(N) << endl;
return 0;
}