华为oj_iNOC产品部-杨辉三角的变形

#include <iostream>
#include <cstring>

using namespace std;

int main()
{
    int n,i,k;
    int *a,*b;
    while(cin>>n)
    {
        a=new int[2*n+1];
        b=new int[2*n+1];
        for(i=0;i<2*n+1;i++)
            a[i]=b[i]=0;
        a[n]=1;
        for(k=1;k<n;k++)
        {
            if(k%2==1)
            {
                for(i=1;i<2*n;i++)
                    b[i]=a[i-1]+a[i]+a[i+1];
            }
            else
            {
                for(i=1;i<2*n;i++)
                    a[i]=b[i-1]+b[i]+b[i+1];
            }
        }
        k=0;
        if(n%2==1)
        {
            for(i=1;i<2*n+1;i++)
            {
                if(a[i]!=0&&a[i]%2==0)
                {
                    cout<<i<<endl;
                    k=1;
                    break;
                }
            }
        }
        else
        {
            for(i=0;i<2*n+1;i++)
            {
                if(b[i]!=0&&b[i]%2==0)
                {
                    cout<<i<<endl;
                    k=1;
                    break;
                }
            }
        }
        if(k==0)
            cout<<-1<<endl;
        delete a;
        delete b;
    }
    return 0;
}