Solution.ts

function containsNearbyDuplicate(nums: number[], k: number): boolean {
    const d: Map<number, number> = new Map();
    for (let i = 0; i < nums.length; ++i) {
        if (d.has(nums[i]) && i - d.get(nums[i])! <= k) {
            return true;
        }
        d.set(nums[i], i);
    }
    return false;
}