hourglass.cpp

#include<iostream>

using namespace std;

int main()
{
    int n;
    cin>>n;
    
    //TOP
    for(int i = 0 ; i < n ; i++)
        cout<<"* ";
    cout<<endl;
    
    //FIRST HALF
    
    int gap = 1;
    
    for(int i = 1 ; i <= n - 1 ; i++)
    {
        int j = 0;
        for( ; j < gap ; j++)
            cout<<" ";
        j = 0;
        for( ; j < n - i ; j++)
            cout<<"* ";
        cout<<endl;
        gap++;
    }
    
    //SECOND HALF
    gap = n - 2; // 3
    
    for(int i = 1 ; i <= n - 2 ; i++)
    {
        int j = 0;
        for( ; j < gap ; j++)
            cout<<" ";
        j = 0;
        for( ; j < i+1  ; j++)
            cout<<"* ";
        gap--;
        cout<<endl;
    }
    
    //BOTTOM
    for(int i = 0 ; i < n ; i++)
        cout<<"* ";
    cout<<endl;
}