The sortDesc function combines two arrays arr1 and arr2 and sorts the concatenated array in descending order. However, the code then attempts to check each element in the sorted array to ensure it is greater than the previous one, throwing an error if this condition is not met, which suggests a logical flaw in the code logic.

Cell 2

var arr1 = [1, 3, 2, 7];
var arr2 = [9, 11, 4, 6];

function sortDesc(arr1, arr2) {
  return arr1.concat(arr2).sort((a, b) => b-a);
}

var result = sortDesc(arr1, arr2);
console.log(result)


// [ 11, 9, 7, 6, 4, 3, 2, 1 ]
var prev = Number.MAX_VALUE;
result.forEach(r => {
  if(r > prev) {
    throw new Error('this doesnt work');
  }
})

/**
 * Merges two arrays and sorts the result in descending order.
 * Throws an error if the resulting array is not strictly sorted in descending order.
 * 
 * @param {Array<number>} arr1 The first array to merge.
 * @param {Array<number>} arr2 The second array to merge.
 * @returns {Array<number>} The sorted array of merged numbers.
 */
function sortDescending(arr1, arr2) {
    // Check for invalid input types
    if (!Array.isArray(arr1) ||!Array.isArray(arr2)) {
        throw new Error('Both inputs must be arrays');
    }
    if (!arr1.every(Number.isFinite) ||!arr2.every(Number.isFinite)) {
        throw new Error('Arrays must only contain numbers');
    }

    // Merge the arrays and sort in descending order
    const merged = [...arr1,...arr2].sort((a, b) => b - a);

    // Check if the array is sorted in descending order
    const prev = Number.MIN_VALUE;
    for (const num of merged) {
        if (num <= prev) {
            throw new Error('Array is not strictly sorted in descending order');
        }
        prev = num;
    }

    return merged;
}

// Example usage:
const arr1 = [1, 3, 2, 7];
const arr2 = [9, 11, 4, 6];
const result = sortDescending(arr1, arr2);
console.log(result);

Code Breakdown

Variables

• arr1: an array of integers [1, 3, 2, 7]
• arr2: an array of integers [9, 11, 4, 6]

Function

• sortDesc(arr1, arr2): a function that sorts the concatenated arrays in descending order
  • Uses the concat() method to combine arr1 and arr2
  • Uses the sort() method with a compare function (a, b) => b-a to sort the combined array in descending order
  • Returns the sorted array

Logic

• result: the output of the sortDesc() function
• prev: initialized to the maximum possible integer value (Number.MAX_VALUE)
• The code loops through each element of the result array and checks if it is greater than the previous element (prev)
  • If the current element is not greater than the previous element, it throws an error with the message 'this doesnt work'