Problem Statement: Given an integer N, print the following pattern :
Here, N = 5.
Examples:
Input Format: N = 3
Result:
*
***
*****
*****
***
*
Input Format: N = 6
Result:
*
***
*****
*******
*********
***********
***********
*********
*******
*****
***
*
Solution
Disclaimer: Don’t jump directly to the solution, try it out yourself first.
Approach:
There are 4 general rules for solving a pattern-based question :
- We always use nested loops for printing the patterns. For the outer loop, we count the number of lines/rows and loop for them.
- Next, for the inner loop, we focus on the number of columns and somehow connect them to the rows by forming a logic such that for each row we get the required number of columns to be printed.
- We print the ‘*’ inside the inner loop.
- Observe symmetry in the pattern or check if a pattern is a combination of two or more similar patterns or not.
This pattern is just a mixture of the last two patterns ( erect pyramid and inverted pyramid). Firstly, we will print the erect pyramid and then an inverted pyramid below it.
Code:
C++ Code
#include <bits/stdc++.h>
using namespace std;
void erect_pyramid(int N)
{
// This is the outer loop which will loop for the rows.
for (int i = 0; i < N; i++)
{
// For printing the spaces before stars in each row
for (int j =0; j<N-i-1; j++)
{
cout <<" ";
}
// For printing the stars in each row
for(int j=0;j< 2*i+1;j++){
cout<<"*";
}
// For printing the spaces after the stars in each row
for (int j =0; j<N-i-1; j++)
{
cout <<" ";
}
// As soon as the stars for each iteration are printed, we move to the
// next row and give a line break otherwise all stars
// would get printed in 1 line.
cout << endl;
}
}
void inverted_pyramid(int N)
{
// This is the outer loop which will loop for the rows.
for (int i = 0; i < N; i++)
{
// For printing the spaces before stars in each row
for (int j =0; j<i; j++)
{
cout <<" ";
}
// For printing the stars in each row
for(int j=0;j< 2*N -(2*i +1);j++){
cout<<"*";
}
// For printing the spaces after the stars in each row
for (int j =0; j<i; j++)
{
cout <<" ";
}
// As soon as the stars for each iteration are printed, we move to the
// next row and give a line break otherwise all stars
// would get printed in 1 line.
cout << endl;
}
}
int main()
{
// Here, we have taken the value of N as 5.
// We can also take input from the user.
int N = 5;
erect_pyramid(N);
inverted_pyramid(N);
return 0;
}
Output
*
***
*****
*******
*********
*********
*******
*****
***
*
Java Code
class Main {
static void erect_pyramid(int N)
{
// This is the outer loop which will loop for the rows.
for (int i = 0; i < N; i++)
{
// For printing the spaces before stars in each row
for (int j =0; j<N-i-1; j++)
{
System.out.print(" ");
}
// For printing the stars in each row
for(int j=0;j< 2*i+1;j++){
System.out.print("*");
}
// For printing the spaces after the stars in each row
for (int j =0; j<N-i-1; j++)
{
System.out.print(" ");
}
// As soon as the stars for each iteration are printed, we move to the
// next row and give a line break otherwise all stars
// would get printed in 1 line.
System.out.println();
}
}
static void inverted_pyramid(int N)
{
// This is the outer loop which will loop for the rows.
for (int i = 0; i < N; i++)
{
// For printing the spaces before stars in each row
for (int j =0; j<i; j++)
{
System.out.print(" ");
}
// For printing the stars in each row
for(int j=0;j< 2*N -(2*i +1);j++){
System.out.print("*");
}
// For printing the spaces after the stars in each row
for (int j =0; j<i; j++)
{
System.out.print(" ");
}
// As soon as the stars for each iteration are printed, we move to the
// next row and give a line break otherwise all stars
// would get printed in 1 line.
System.out.println();
}
}
public static void main(String[] args) {
// Here, we have taken the value of N as 5.
// We can also take input from the user.
int N = 5;
erect_pyramid(N);
inverted_pyramid(N);
}
}
Output
*
***
*****
*******
*********
*********
*******
*****
***
*
Special thanks to Priyanshi Goel for contributing to this article on takeUforward. If you also wish to share your knowledge with the takeUforward fam, please check out this article. If you want to suggest any improvement/correction in this article please mail us at [email protected]