题解

从A654（catch that cow）的题解改的：

#include <bits/stdc++.h>
using namespace std;
int main(){
    int t;
    cin >> t;
    while(t--){
        int n , k;
    	cin >> n >> k;
        queue<int> q;
        q.push(n);
        int vis[100005] = {0};
        int d[100005] = {0};
    	while(!q.empty()){
    		int t = q.front();
    		q.pop();
    		if(t == k){
        		cout << d[t] << endl;
    		}
    		if(t + 1 <= 100000 && vis[t + 1] != 1){
    			vis[t + 1] = 1;
    			d[t + 1] = d[t] + 1;
    			q.push(t + 1);
    		} 
    		if(t - 1 >= 0 && vis[t - 1] != 1){
    			vis[t - 1] = 1;
    			d[t - 1] = d[t] + 1;
    			q.push(t - 1);
    		}
    		if(t * 2 <= 100000 && vis[t * 2] != 1){
    			vis[t * 2] = 1;
    			d[t * 2] = d[t] + 1;
    			q.push(t * 2);
    		}
    		
    	}
    }
	return 0;
}