题解

#include<bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
struct node {
	int x, d; 
};
int n, k;  
bool inq[N]; 
int BFS(int x) {
	queue<node> q;
	q.push({x, 0});
	inq[x] = true;
	while(!q.empty()) {
		node t = q.front();
		q.pop();
		if(t.x == k) return t.d;
		int nx = t.x - 1;  
		if(nx >= 0 && !inq[nx]) {
			q.push({nx, t.d + 1});
			inq[nx] = true;
		}
		nx = t.x + 1;  
		if(nx <= 100000 && !inq[nx]) {
			q.push({nx, t.d + 1});
			inq[nx] = true;
		}
		nx = t.x * 2;  
		if(nx <= 100000 && !inq[nx]) {
			q.push({nx, t.d + 1});
			inq[nx] = true;
		}
	}
}
int main() {
	cin >> n >> k;
	cout << BFS(n);
	return 0;
}