Step by Step solution about How to resolve the algorithm Jewels and stones step by step in the JavaScript programming language

Explanation:

Function:

• jewelCount: This function counts the number of jewels in a given string.
  • Parameters:
    • j: A string containing the types of jewels to count.
    • s: A string containing the input string.
  • Returns: An integer representing the number of jewels in the input string.

Implementation:

• The function splits the input string of jewels (j) into an array of individual characters (js).
• It then splits the input string (s) into an array of individual characters.
• The reduce method is used to iterate over each character in the input string and check if it is present in the array of jewels (js).
  • If the character is present, the accumulator (a) is incremented by 1.
  • Otherwise, the accumulator remains unchanged.
• The initial value of the accumulator is set to 0, representing the initial count of jewels.

Test Cases:

• The provided test cases are:
  • ["aA", "aAAbbbb"]: In this case, there are 3 jewels (a and 2 As) in the input string, so the result is 3.
  • ["z", "ZZ"]: In this case, there are 2 jewels (z and Z) in the input string, so the result is 2.

Usage:

The code is wrapped in an immediately invoked function expression (IIFE) to create a private scope. The function jewelCount is exported by returning the array of results from the test cases.

(() => {

    // jewelCount :: String -> String -> Int
    const jewelCount = (j, s) => {
        const js = j.split('');
        return s.split('')
            .reduce((a, c) => js.includes(c) ? a + 1 : a, 0)
    };

    // TEST -----------------------------------------------
    return [
            ['aA', 'aAAbbbb'],
            ['z', 'ZZ']
        ]
        .map(x => jewelCount(...x))
})();