java

find-lucky-numbers-range()

Parameters: int lowerBound, int upperBound

Two integers representing the lower and upper bounds of the range.

Returns: An ArrayList<Integer> of lucky numbers within the given range.

This function accepts two integer parameters representing the start and end of a range, then returns a list of all lucky numbers within this range.

Variables
Loops
Conditional Statements
Lists
Functions
Medium dificulty

Creating a Function to Find Lucky Numbers within a Given Range in Java

Hello programmer! In this blog post, we're about to embark on a unique programming adventure. This feat involves creating a function written in Java, specifically designed for finding 'lucky numbers' within a specified range. Follow along and widen your programming horizons. Let your skills shine through this educative instance. The steps to accomplish this are outlined below. Happy Coding!

Step 1: Define the function skeleton

Start by defining the function skeleton in Java. The function findLuckyNumbersInRange takes in two integers as arguments, start and end, representing the start and end of the range, respectively.

public static ArrayList<Integer> findLuckyNumbersInRange(int start, int end) {
    // logic here
}

Step 2: Initialize an ArrayList

Inside the function, create an ArrayList to store the lucky numbers. Let's call it luckyNumbers.

public static ArrayList<Integer> findLuckyNumbersInRange(int start, int end) {
    ArrayList<Integer> luckyNumbers = new ArrayList<>();
    // logic here
}

Step 3: Loop through the range

Create a loop to go through each number in the range from start to end.

public static ArrayList<Integer> findLuckyNumbersInRange(int start, int end) {
    ArrayList<Integer> luckyNumbers = new ArrayList<>();
    for (int i = start; i <= end; i++) {
        // logic here
    }
}

Step 4: Check if a number is lucky

A lucky number is a number that contains the digit 7. Therefore, convert each number to a string and check if it contains '7'. If it does, add it to luckyNumbers.

public static ArrayList<Integer> findLuckyNumbersInRange(int start, int end) {
    ArrayList<Integer> luckyNumbers = new ArrayList<>();
    for (int i = start; i <= end; i++) {
        if (String.valueOf(i).contains("7")) {
            luckyNumbers.add(i);
        }
    }
}

Step 5: Return the list of lucky numbers

Finally, return the luckyNumbers ArrayList.

Below is the final implementation of the findLuckyNumbersInRange function. With this function, we can find all the lucky numbers in a specified range.

public static ArrayList<Integer> findLuckyNumbersInRange(int start, int end) {
    ArrayList<Integer> luckyNumbers = new ArrayList<>();
    for (int i = start; i <= end; i++) {
        if (String.valueOf(i).contains("7")) {
            luckyNumbers.add(i);
        }
    }
    return luckyNumbers;
}

Learn function in:

Finding lucky numbers within a range

A function that outputs all lucky numbers within a specified range.

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Mathematical principle

The principle of this problem is built on the concept of 'Lucky Numbers', a series of numbers generated using a specific elimination process. For `find-lucky-numbers-range`, we iterate through the range and apply a certain filter to determine if the number is 'lucky'. Each iteration increases the number to be eliminated.

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