两个小问题（想不出标题了）

#include<iostream>
#include<algorithm>
#include<stdio.h>
#include<cstdio>

#include<vector>
#include<queue>

using namespace std;

int n;

bool check(int x){
	if(x<=0||x>n){
		return false;
	}
	else{
		return true;
	}
}

void bfs(){
	queue <int> q;
	vector <int> dis(n,-1);
	vector <bool> vis(n,false);
	q.push(1);
	dis[1]=0;
	vis[1]=true;
	while(!q.empty()){
		int cur=q.front();
		q.pop();
		if(check(cur+1)&&!vis[cur+1]){
			vis[cur+1]=true;
			q.push(cur+1);
			dis[cur+1]=dis[cur]+1;
		}
		if(check(cur-1)&&!vis[cur-1]){
			vis[cur-1]=true;
			q.push(cur-1);
			dis[cur-1]=dis[cur]+1;
		}
		if(check(cur*2)&&!vis[cur*2]){
			vis[cur*2]=true;
			q.push(cur*2);
			dis[cur*2]=dis[cur]+1;
		}
	}
	cout<<dis[n]<<endl;
	return;
}

int main(){
	cin>>n;
	bfs();
//cout<<"error"<<endl;
	return 0;
}

if(check(cur+1)&&!vis[cur+1]){
			vis[cur+1]=true;
			q.push(cur+1);
			dis[cur+1]=dis[cur]+1;
}
if(check(cur-1)&&!vis[cur-1]){
			vis[cur-1]=true;
			q.push(cur-1);
			dis[cur-1]=dis[cur]+1;
}
if(check(cur*2)&&!vis[cur*2]){
			vis[cur*2]=true;
			q.push(cur*2);
			dis[cur*2]=dis[cur]+1;
}

vis[cur]=true;
if(check(cur+1)&&!vis[cur+1]){
			q.push(cur+1);
			dis[cur+1]=dis[cur]+1;
}
if(check(cur-1)&&!vis[cur-1]){
			q.push(cur-1);
			dis[cur-1]=dis[cur]+1;
}
if(check(cur*2)&&!vis[cur*2]){
			q.push(cur*2);
			dis[cur*2]=dis[cur]+1;
}