似是没有发现哪里错了

#include <bits/stdc++.h>
using namespace std;
int n,a[1000005];
queue<int> q;
int main ()
{
	memset (a,-1,sizeof,arr);
	cin >>n;
	a[1] = 0;
	q.push(1);
	while (!q.empty())
	{
		int t = q.front();
		q.pop();
		if (t == n)
		{
			break;
		}
		int x = t-1,y = t+1,z = t*2;
		if (x>=1&&x<=2*n&&a[x] == -1)
		{
			q.push(x);
			a[x] = a[t]+1;
		}
		if (z>=1&&z<=2*n&&a[z] == -1)
		{
			q.push;
			a[z] = a[t]+1;
		}
	}
	cout <<a[n];
	return 0;
}