✅219. 存在重复元素 II about like-algorithms HOT 2 OPEN

/**
 * @param {number[]} nums
 * @param {number} k
 * @return {boolean}
 */
var containsNearbyDuplicate = function (nums, k) {
    let map = new Map();

    for (let index = 0; index < nums.length; index++) {
        const element = nums[index];
        if (map.has(element) && index - map.get(element) <= k) {
            return true;
        } else {
            map.set(element, index);
        }
    }
    return false;
};

/**
 * @param {number[]} nums
 * @param {number} k
 * @return {boolean}
 */
var containsNearbyDuplicate = function(nums, k) {
	const len = nums.length;
	const map = new Map(); // {"num" => index}

	for (let i = 0; i < len; i++) {
		const num = nums[i]
		if (map.has(num) && i - map.get(num) <= k) return true;
		map.set(num, i);
	}
	return false;
};