Contains Duplicate II 解答

Question

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 difference between i and j is at most k.

Solution -- HashMap

public class Solution {
    public boolean containsNearbyDuplicate(int[] nums, int k) {
        int length = nums.length;
        if (length <= 1 || k < 1)
            return false;
        Map<Integer, Integer> map = new HashMap<Integer, Integer>();
        int min = Integer.MAX_VALUE;
        for (int i = 0; i < length; i++) {
            if (map.containsKey(nums[i])) {
                int prev = map.get(nums[i]);
                int gap = i - prev;
                min = Math.min(min, gap);
            }
            map.put(nums[i], i);
        }
        if (min <= k)
            return true;
        else
            return false;
    }
}