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;
     }
 }