MoveNegativeElements.js

/**
 * @author Anirudh Sharma
 * 
 * An array contains both positive and negative numbers in random order. Rearrange the array elements so that all
 * negative numbers appear before all positive numbers.
 */
const moveNegatives = (a) => {
    // Left and right pointers
    let left = 0;
    let right = a.length - 1;
    // Loop through the array until two pointers meet
    while (left <= right) {
        // Case 1: both elements are negative
        if (a[left] < 0 && a[right] < 0) {
            left++;
        }
        // Case 2: If both elements are positive
        else if (a[left] > 0 && a[right] > 0) {
            right--;
        }
        // Case 3: If left is positive and right is negative
        else if (a[left] > 0 && a[right] < 0) {
            // Swap
            let temp = a[left];
            a[left] = a[right];
            a[right] = temp;
            // Update the pointers
            left++;
            right--;
        }
        // Case 4: If left is negative and right is positive
        else {
            left++;
            right--;
        }
    }
    return a;
};


console.log(moveNegatives([-1, 2, -3, 4, 5, 6, -7, 8, 9]));
console.log(moveNegatives([-12, 11, -13, -5, 6, -7, 5, -3, 11]));