bfs 90分求大佬调

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> PII;
#define x first
#define y second

const int N = 1e6 + 10;

int dist[2 * N];
int a;

int bfs (int x) {
	queue<PII> q;
	q.push({0, x});
	dist[x] = 0;
	
	while (q.size()) {
		auto t = q.front();
		q.pop();
		int step = t.x, shu = t.y;
		
		if (shu - 1 >= 0 && dist[shu - 1] == 0x3f3f3f3f) {
			dist[shu - 1] = step + 1;
			q.push({step + 1, shu - 1});
		}
		
		if (shu + 1 <= N && dist[shu + 1] == 0x3f3f3f3f) {
			dist[shu + 1] = step + 1;
			q.push({step + 1, shu + 1});
		}
		
		if (shu * 2 <= N && dist[shu * 2] == 0x3f3f3f3f) {
			dist[shu * 2] = step + 1;
			q.push({step + 1, shu * 2});
		}
		
	}
	return dist[a];
}

int main () {
	
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	
	memset(dist, 0x3f3f3f3f, sizeof dist);
	
	cin >> a;
	cout << bfs(1);
	
	return 0;
}