LeetCode219. Contains Duplicate II

一、题目

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:

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

Input: nums = [1,0,1,1], k = 1
Output: true
Example 3:

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

Constraints:

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

二、题解

class Solution {
public:
    bool containsNearbyDuplicate(vector<int>& nums, int k) {
        int n = nums.size();
        unordered_map<int,int> map;
        for(int i = 0;i < n;i++){
            if(map.find(nums[i]) == map.end()) map[nums[i]] = i;
            else{
                if(abs(map[nums[i]] - i) <= k) return true;
                map[nums[i]] = i;
            }
        }
        return false;
    }
};