C :

int main(){
         int n,i,j,z;
         scanf("%d",&n);
                  for(i = 1;i <= n+1;i++){
                   for(j=1;j <= n-i+1;j++){
                            printf(" ");
                   }
                  
                   for(z = 1;z <= 2 * i-1;z++){
                            printf("*");
                   }
                   printf("\n");
         
         } 
         
                   
                  for(i = n;i >= 1;i--){
                   
                   for(j = 0;j < n-i+1;j++){
                            printf(" ");
                   }
                   
                   for(z=1;z <= 2 * i - 1;z++){
                            printf("*");
                   }
                   
                   printf("\n");
         }
 

         
        
         return n;
}

C++ :

#include <iostream>
using namespace std;

int main(){
	int i,j,n;
	cin>>n;
	n = n + 1;
	for(i = 1;i <= n - 1;i++){
		for(j = 1;j <= n - i;j++){
			cout<<" ";
		}
		
		for(j = 1;j <= 2 * i - 1;j++){
			cout<<"*";
		} 
		cout<<endl;
	}
	
	for(i = n;i >= 1;i--){
		for(j = 1;j <= n - i;j++){
			cout<<" ";
		}
		
		for(j = 1;j <= 2 * i - 1;j++){
			cout<<"*";
		} 
		cout<<endl;
	}
	return 0;
}

Python :

n = int(input());
n = n+1
for a in range (1, n + 1):
    for b in range (1, n - a +1):
        print('',end=' ')
    for c in range (1, 2*a):
        print('*',end='')
    print()
for i in range(2, n + 2):
    for k in range(2, i+1):
        print(end=' ')
    for x in range(i ,2*n-i+1 ):
        print('*', end = '')
    print()