Pattern 9

Pattern 9

Beginner Problems Patterns Easy

While developing console-based games, animations, or other graphical representations in terminal, such pattern creation problems come handy
They give an understanding of how to use control structures (like loops) for producing repetitive and patterned output
These concepts are fundamental in developing console output display features in many kinds of software
The ability to create and manipulate these patterns can be extended to more complex graphics rendering challenges

Given an integer n. You need to recreate the pattern given below for any value of N. Let's say for N = 5, the pattern should look like as below:

    * 
   ***
  *****
 *******
*********
*********
 *******
  *****
   ***
    *

Print the pattern in the function given to you.

Constraints

1 <= n <= 20

Company Tags

TCS Cognizant Accenture Infosys Capgemini Wipro IBM HCL Tech Mahindra MindTree

Editorial

Approach:

This pattern is a combination of the pyramid and an inverted pyramid. First print the pyramid and then the inverted one.

Use nested for loops to print the pyramid, first print the spaces using a for loop, then require asterisks using a second for loop and finally print the spaces again in a different loop.

After this, give a line break to print the next row. Follow the same process to print the inverted pyramid.

#include <bits/stdc++.h>
using namespace std;

class Solution {
public:
    // Function to print pattern9
    static void pattern9(int n) {
        erect_pyramid(n);
        inverted_pyramid(n);
    }
private: 
    static void erect_pyramid(int n) {
        // 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 */
            cout << endl;
        }
    }
    static void inverted_pyramid(int n){
        // 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 */
            cout<< endl;
    }
}
        
};

int main() {
    int N = 5;

    //Create an instance of Solution class
    Solution sol;

    sol.pattern9(N);

    return 0;
}
class Solution {
    // Function to print pattern9
    public static void pattern9(int n) {
        erectPyramid(n);
        invertedPyramid(n);
    }

    private static void erectPyramid(int n) {
        // 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 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 */
            System.out.println();
        }
    }

    private static void invertedPyramid(int n) {
        // 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 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 */
            System.out.println();
        }
    }

    public static void main(String[] args) {
        int N = 5;

        // Create an instance of Solution class
        Solution sol = new Solution();

        sol.pattern9(N);
    }
}
class Solution:
    def pattern9(self, n):
        self.erect_pyramid(n)
        self.inverted_pyramid(n)

    def erect_pyramid(self, n):
        # Outer loop which will loop for the rows.
        for i in range(n):
            # For printing the spaces before stars in each row
            for j in range(n - i - 1):
                print(" ", end="")

            # For printing the stars in each row
            for j in range(2 * i + 1):
                print("*", end="")

            # For printing the spaces after stars in each row
            for j in range(n - i - 1):
                print(" ", end="")

            # As soon as the stars for each iteration are printed,
            # we move to the next row and give a line break
            print()

    def inverted_pyramid(self, n):
        # Outer loop which will loop for the rows.
        for i in range(n):
            # For printing the spaces before stars in each row
            for j in range(i):
                print(" ", end="")

            # For printing the stars in each row
            for j in range(2 * n - (2 * i + 1)):
                print("*", end="")

            # For printing the spaces after stars in each row
            for j in range(i):
                print(" ", end="")

            """ As soon as the stars for each iteration are printed,
            we move to the next row and give a line break"""
            print()

if __name__ == "__main__":
    N = 5

    # Create an instance of Solution class
    sol = Solution()

    sol.pattern9(N)
class Solution {
    // Function to print pattern9
    pattern9(n) {
        this.erectPyramid(n);
        this.invertedPyramid(n);
    }

    erectPyramid(n) {
        // Outer loop which will loop for the rows.
        for (let i = 0; i < n; i++) {
            // For printing the spaces before stars in each row
            for (let j = 0; j < n - i - 1; j++) {
                process.stdout.write(" ");
            }

            // For printing the stars in each row
            for (let j = 0; j < 2 * i + 1; j++) {
                process.stdout.write("*");
            }

            // For printing the spaces after stars in each row
            for (let j = 0; j < n - i - 1; j++) {
                process.stdout.write(" ");
            }

            /* As soon as the stars for each iteration are printed,
            we move to the next row and give a line break */
            console.log();
        }
    }

    invertedPyramid(n) {
        // Outer loop which will loop for the rows.
        for (let i = 0; i < n; i++) {
            // For printing the spaces before stars in each row
            for (let j = 0; j < i; j++) {
                process.stdout.write(" ");
            }

            // For printing the stars in each row
            for (let j = 0; j < 2 * n - (2 * i + 1); j++) {
                process.stdout.write("*");
            }

            // For printing the spaces after stars in each row
            for (let j = 0; j < i; j++) {
                process.stdout.write(" ");
            }

            /* As soon as the stars for each iteration are printed,
            we move to the next row and give a line break */
            console.log();
        }
    }
}

// Main program
let N = 5;

// Create an instance of Solution class
let sol = new Solution();

sol.pattern9(N);

Complexity Analysis:

Time Complexity : O(2*N²). As both functions take O(N²) each.

Space Complexity :O(1). As no extra space is being used to print the patterns.

Code