219. Contains Duplicate II

use hashmap

class Solution {
    public boolean containsNearbyDuplicate(int[] nums, int k) {
        Map<Integer, Integer> map = new HashMap<>();
        for (int i = 0; i < nums.length; i++) {
            if (map.containsKey(nums[i]) && (map.get(nums[i]) - i) <= k) {
                return true;
            }
            map.put(nums[i], i);
        }
        return false;
    }
}

/*
i != j

abs(i-j) <= k

T: O(n)
S: O(n)

*/

python - use hashmap

class Solution:
    def containsNearbyDuplicate(self, nums: List[int], k: int) -> bool:
        dict = {}
        for i, v in enumerate(nums):
            if v in dict and i - dict[v] <= k:
                return True
            dict[v] = i
        return False