DSA using JavaScript

Time Complexity: O(n)
Space Complexity: O(1)

Binary Search

function findClosestBruteForce(arr, target) {
    let minDiff = Infinity;
    let closestElement = arr[0];

    for (let i = 0; i < arr.length; i++) {
        let diff = Math.abs(arr[i] - target);
        if (diff < minDiff) {
            minDiff = diff;
            closestElement = arr[i];
        }
    }
    
    return closestElement;
}

const arr = [1, 3, 5, 8, 12, 15];
const target = 7;
console.log(findClosestBruteForce(arr, target));  // Output: 8

function findClosestBinarySearch(arr, target) {
    let left = 0, right = arr.length - 1;

    if (target <= arr[0]) return arr[0];
    if (target >= arr[arr.length - 1]) return arr[arr.length - 1];
    
    while (left <= right) {
        let mid = Math.floor((left + right) / 2);
        
        if (arr[mid] === target) {
            return arr[mid];
        } else if (arr[mid] < target) {
            left = mid + 1;
        } else {
            right = mid - 1;
        }
    }
    
    // At this point, left is greater than right, and the target lies between arr[right] and arr[left]
    if ((target - arr[right]) <= (arr[left] - target)) {
        return arr[right];
    } else {
        return arr[left];
    }
}

const arr = [1, 3, 5, 8, 12, 15];
const target = 7;
console.log(findClosestBinarySearch(arr, target));  // Output: 8