C :

#include<stdio.h>
void main()
{
	int n;
	scanf("%d",&n);
	int a;//hang上半部分 
	for(a=1;a<=(n+1)/2;a++){
		
		int b;//kongge
		for(b=1;b<=a-1;b++){
			printf(" ");
		}
		int c;
		for(c=1;c<=n;c++){
			printf("*");
		}
	printf("\n");
	}
	//下半部分
	int d;
	for(d=1;d<=n/2;d++){
		
		int e=1;//kongge
		for(;e<=n/2-d;e++){
			printf(" "); 
		}
		int c;
		for(c=1;c<=n;c++){
			printf("*");
		}
		printf("\n");
	}
	 
}

C++ :

#include <iostream>
#include <cstring>
using namespace std;

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

Python :

n = int(input())
for i in range(0, n):
    if(i < n - 2):
        print(" " * i, end="")
        print("*" * n)
    else:
        print(" " * (n - i - 1), end="")
        print("*" * n)