219. Contains Duplicate II

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219. Contains Duplicate II

Description

Difficulty: Easy

Related Topics: Array, Hash Table, Sliding Window

Given an integer array nums and an integer k, return true if there are two distinct indices i and j in the array such that nums[i] == nums[j] and abs(i - j) <= k.

Example 1:

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Input: nums = [1,2,3,1], k = 3
Output: true

Example 2:

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Input: nums = [1,0,1,1], k = 1
Output: true

Example 3:

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Input: nums = [1,2,3,1,2,3], k = 2
Output: false

Constraints:

  • 1 <= nums.length <= 105
  • -109 <= nums[i] <= 109
  • 0 <= k <= 105

Hints/Notes

Solution

Language: C++

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class Solution {
public:
    bool containsNearbyDuplicate(vector<int>& nums, int k) {
        int left = 0, right = 0;
        map<int, int> m;
        while (right < nums.size()) {
            if (m[nums[right]] > 0) {
                return true;
            }
            m[nums[right]]++;
            right++;
            if (right - left > k) {
                m[nums[left]]--;
                left++;
            }
        }   
        return false;
    }
};