C :

#include <stdio.h>
#include <stdlib.h>
int main()
{
	int n;
	scanf("%d",&n);
	int i,j;
	for(i=1;i<n;i++)
		printf(" ");
    for(i=0;i<n;i++)
		printf("*");
	printf("\n");
    for(i=1;i<n;i++)
	{
        for(j=1;j<n-i;j++)
			printf(" ");
        printf("*");
        for(j=0;j<n+2*(i-1);j++)
			printf(" ");
        printf("*");
        printf("\n");
    }
    for(i=1;i<=n-2;i++)
	{
        for(j=0;j<i;j++)
			printf(" ");
        printf("*");
        for(j=0;j<n+(n-2-i)*2;j++)
			printf(" ");
        printf("*");
        printf("\n");
    }
    for(i=1;i<n;i++)
		printf(" ");
    for(i=0;i<n;i++)
		printf("*");
    return 0;
}
//Author: ITProgrammer

C++ :

#include <iostream>
#include <cmath>
#include <iomanip>

using namespace std;

int main(){
    int i,j,n;
    cin>>n;
    for(i=1;i<n;i++){
    	cout<<" ";
	}
	for(i=1;i<=n;i++){
		cout<<"*";
	}
	cout<<endl;
    for(i=2;i<=n;i++){
    	for(j=1;j<=n-i;j++){
    		cout<<" ";
		}
		cout<<"*";
		for(j=1;j<=n+(i-2)*2;j++){
			cout<<" ";
		}
		cout<<"*"<<endl;
	}
	for(i=n-1;i>=2;i--){
		for(j=1;j<=n-i;j++){
    		cout<<" ";
		}
		cout<<"*";
		for(j=1;j<=n+(i-2)*2;j++){
			cout<<" ";
		}
		cout<<"*"<<endl;
	}
	for(i=1;i<n;i++){
    	cout<<" ";
	}
	for(i=1;i<=n;i++){
		cout<<"*";
	}
	cout<<endl;
}

Python :

#!/usr/bin/env python3

n = int(input())
k = n
m = n - 1

for i in range(0,m,1):
	print("",end=" ")
m -= 1;

for i in range(0,n,1):
	print("*",end="")
print("")
for i in range(0,n-1,1):
	for j in range(0,m,1):
		print("",end=" ")
	print("*",end="")
	for x in range(0,k,1):
		print("",end=" ")
	print("*")
	k+=2
	m-=1
k-=4
m+=2
for i in range(0,n-2,1):
	for j in range(0,m,1):
		print("",end=" ")
	print("*",end="")
	for x in range(0,k,1):
		print("",end=" ")
	print("*")
	k-=2
	m+=1	
for i in range(0,m,1):
	print("",end=" ")
for i in range(0,n,1):
	print("*",end="")
print("")