Palantir Interview Questions

Question: Array Contains Duplicate

//Given an array of integers, find if the array contains any duplicates. Your function should return 
//true if any value appears at least twice in the array, and it should return false if every element is distinct.
class ContainsDuplicate {
    public boolean containsDuplicate(int[] nums) {
        HashMap<Integer, Integer> map = new HashMap<Integer, Integer>();
        for(int i: nums) {
            if(map.containsKey(i)) {
                return true;
            } else {
                map.put(i, 1);
            }
        }
        
        return false;
    }
}

Question: Array Contains Duplicate II

//Given an array of integers and an integer k, find out whether there are two distinct indices i and 
//j in the array such that nums[i] = nums[j] and the absolute difference between i and j is at most k.
class ContainsDuplicatesII {
    public boolean containsNearbyDuplicate(int[] nums, int k) {
        HashMap<Integer, Integer> map = new HashMap<Integer, Integer>();
        for(int i = 0; i < nums.length; i++) {
            int current = nums[i];
            if(map.containsKey(current) && i - map.get(current) <= k) {
                return true;
            } else {
                map.put(current, i);
            }
        }
        
        return false;
    }
}