These two questions were posted by a LinkedIn user, and I thought of solving them. Two unique problems: one about converting a string from CamelCase to SnakeCase, and the other about finding common numbers in an array. In this blog, I’ll write my approach to solving these problems step by step.

Program 1 : Converting CamelCase to SnakeCase

Converting a camel case sentence to a snake case sentenced
Input -->sentence="MyNameIsAswin"
Output --> My_Name_Is_Aswin

My Approach:

To solve this, I wrote a simple method that traverses through the input string, checks for uppercase letters, and inserts an underscore before them to convert it to SnakeCase.

Link - LinkedIn | Post

// Question 1 Helper Method
public static String convertToSnakeCase(String str){
    StringBuilder sb = new StringBuilder();
    sb.append(str.charAt(0));  // Start with the first character

    for (int i = 1; i < str.length(); i++) {
        char ch = str.charAt(i);
        if (Character.isUpperCase(ch)) {
            sb.append("_");  // Add underscore before an uppercase letter
        }
        sb.append(ch);  // Append the current character
    }
    return sb.toString();
}

Problem 2: Finding Common Numbers in an Array

Print the count of common numbers in an array with size 3
Input-->arr=[5,3,2]
Output-->0
Input-->arr=[2,5,2]
Output-->2
Input-->arr=[5,5,5]
Output-->3

My Approach:

I used a HashMap to store the frequency of each element in the array and then returning the highest frequency.

// Question 2 Helper Method
public static int findCommonNum(int[] arr) {
    Map<Integer, Integer> map = new HashMap<>();

    // Count the frequency of each number
    for (int ele : arr) {
        map.put(ele, map.getOrDefault(ele, 0) + 1);
    }

    // Find the maximum frequency
    int answer = 0;
    for (int value : map.values()) {
        if (value > answer) {
            answer = value;
        }
    }

    // Return 0 if all elements are unique
    return (answer == 1) ? 0 : answer;
}

Full Code Example:

Here’s the complete code implementing both solutions:

import java.util.*;

class HelloWorld {
    public static void main(String[] args) {
        // Question 1
        String sentence = "MyNameIsAswin";
        String result = convertToSnakeCase(sentence);
        System.out.println(result);

        // Question 2
        int[] input = {2, 1, 6};
        int answer = findCommonNum(input);
        System.out.println(answer);
    }

    // Question 1 Helper Method
    public static String convertToSnakeCase(String str){
        StringBuilder sb = new StringBuilder();
        sb.append(str.charAt(0));

        for (int i = 1; i < str.length(); i++) {
            char ch = str.charAt(i);
            if (Character.isUpperCase(ch)) {
                sb.append("_");
            }
            sb.append(ch);
        }
        return sb.toString();
    }

    // Question 2 Helper Method
    public static int findCommonNum(int[] arr) {
        Map<Integer, Integer> map = new HashMap<>();

        for (int ele : arr) {
            map.put(ele, map.getOrDefault(ele, 0) + 1);
        }

        int answer = 0;
        for (int value : map.values()) {
            if (value > answer) {
                answer = value;
            }
        }

        return (answer == 1) ? 0 : answer;
    }
}