Pattern 17

Pattern 17

Beginner Problems Patterns Easy

This programming problem essentially tests the concept of pattern/problem recognition and string manipulation, which are vital in many areas of software development
For instance, in data analysis or processing platforms, there often are requirements to detect and manipulate data patterns
Moreover, in various machine learning models such as natural language processing, the concept of pattern recognition and string manipulation is extensively used to train the models to understand, recognize, and generate human-like text

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:

    A
   ABA
  ABCBA
 ABCDCBA
ABCDEDCBA

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:

Use a for loop to iterate from 0 to N-1, where N is the number of rows. This loop will ensure each row of the pattern is printed.

First, print the spaces needed before the characters in each row using an inner loop. Then, using another loop, print the alphabet characters. As observed from the pattern, the alphabet characters need to be printed incrementally up to a certain point (breakpoint) in every row, and then they need to be printed in a decreasing manner.

After that, print the spaces that are needed after the characters for each row. Upon completion of a row, give a line break to ensure the next row is printed correctly.

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

class Solution {
public:
    //Function to print pattern17
    void pattern17(int n) {
        // Outer loop for the number of rows.
        for(int i = 0; i < n; i++) {
            
            // Printing spaces before characters.
            for(int j = 0; j < n - i - 1; j++) {
                cout << " ";
            }
            
            // Printing characters.
            char ch = 'A';
            int breakpoint = (2 * i + 1) / 2;
            for(int j = 1; j <= 2 * i + 1; j++) {
                cout << ch;
                if(j <= breakpoint)
                    ch++;
                else
                    ch--;
            }
            
            // Printing spaces after characters.
            for(int j = 0; j < n - i - 1; j++) {
                cout << " ";
            }
            
            // Move to the next line for the next row.
            cout << endl;
        }
    }
};

int main() {
    int N = 5;
    
    //Create an instance of Solution class
    Solution sol;
    
    sol.pattern17(N);
    
    return 0;
}
import java.util.*;
class Solution {
    // Function to print pattern17
    public void pattern17(int n) {
        // Outer loop for the number of rows.
        for (int i = 0; i < n; i++) {
            
            // Printing spaces before characters.
            for (int j = 0; j < n - i - 1; j++) {
                System.out.print(" ");
            }

            // Printing characters.
            char ch = 'A';
            int breakpoint = (2 * i + 1) / 2;
            for (int j = 1; j <= 2 * i + 1; j++) {
                System.out.print(ch);
                if (j <= breakpoint)
                    ch++;
                else
                    ch--;
            }

            // Printing spaces after characters.
            for (int j = 0; j < n - i - 1; j++) {
                System.out.print(" ");
            }

            // Move to the next line for the next row.
            System.out.println();
        }
    }

    public static void main(String[] args) {
        int N = 5;
        
        //Create an instance of Solution class
        Solution sol = new Solution();
        
        sol.pattern17(N);
    }
}
class Solution:
    # Function to print pattern17
    def pattern17(self, n):
        # Outer loop for the number of rows.
        for i in range(n):
            
            # Printing spaces before characters.
            for j in range(n - i - 1):
                print(" ", end="")
            
            # Printing characters.
            ch = 'A'
            breakpoint = (2 * i + 1) // 2
            for j in range(1, 2 * i + 2):
                print(ch, end="")
                if j <= breakpoint:
                    ch = chr(ord(ch) + 1)
                else:
                    ch = chr(ord(ch) - 1)
            
            # Printing spaces after characters.
            for j in range(n - i - 1):
                print(" ", end="")
            
            # Move to the next line for the next row.
            print()

if __name__ == "__main__":
    N = 5
    
    #Create an instance of Solution class
    sol = Solution()
    
    sol.pattern17(N)
class Solution {
    // Function to print pattern17
    pattern17(n) {
        // Outer loop for the number of rows.
        for (let i = 0; i < n; i++) {
            
            // Printing spaces before characters.
            for (let j = 0; j < n - i - 1; j++) {
                process.stdout.write(" ");
            }

            // Printing characters.
            let ch = 'A';
            let breakpoint = Math.floor((2 * i + 1) / 2);
            for (let j = 1; j <= 2 * i + 1; j++) {
                process.stdout.write(ch);
                if (j <= breakpoint)
                    ch = String.fromCharCode(ch.charCodeAt(0) + 1);
                else
                    ch = String.fromCharCode(ch.charCodeAt(0) - 1);
            }

            // Printing spaces after characters.
            for (let j = 0; j < n - i - 1; j++) {
                process.stdout.write(" ");
            }

            // Move to the next line for the next row.
            console.log();
        }
    }
}

let N = 5;

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

sol.pattern17(N);

Complexity Analysis:

Time Complexity : O(N²). The overall complexity will be O(N²), due to nested loops iterating over each row for spaces and characters to be printed. Where N is the number of rows.

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

Code