全排列C++

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath> 
#include <vector>
#include <queue>
#include <map>
#include <stack>
#include <set>
#include <sstream>
#include <iomanip> 
using namespace std;

int result = 0;
int a[30];
void output(int n)
{
	int i;
	for(i=0;i<=n-1;i++)
 	{
  		if (i < n - 2)
		{
			if (a[i] == 1 && a[i + 1] == 0 && a[i + 2] == 1)
			{
				return;
			}
		}
		if (i == n - 1)
		{
			result++;
		}
 	}
}

void search(int m,int n)                                     
{
 	int i;
	if(m==n)
 	{
  		output(n);
 	}
 	else
 	{
  		for(i=0;i<=1;i++)
  		{
   			a[m]=i;
   			search(m+1,n);
  		}
 	}
}

int main()
{
	int array[30]={0,2,4,7,12,21,37,65,114,200,351,616,1081,1897,3329,5842,10252,17991,31572,55405,97229,170625,299426,525456,922111,1618192};
	int n;
	cin>>n;
	search(0,n);
	if(array[n] != result)cout<<"error"<<endl;
	cout<<result<<endl;
	result = 0;
	return 0;
}