# 219. Contains Duplicate II
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 absolute difference between i and j is at most 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
# Solution
Approach 1: Hash table.
# Code (Python)
Approach 1:
# Code (C++)
Approach 1:
class Solution {
public:
bool containsNearbyDuplicate(vector<int>& nums, int k) {
unordered_map<int,int> numsMap;
for (int i = 0; i < nums.size(); ++i)
{
if (numsMap.find(nums[i]) != numsMap.end())
{
if (abs(numsMap[nums[i]] - i) <= k)
return true;
}
numsMap[nums[i]] = i;
}
return false;
}
};
class Solution {
public:
bool containsNearbyDuplicate(vector<int>& nums, int k) {
unordered_set<int> numsSet;
for (int i = 0; i < nums.size(); ++i)
{
if (numsSet.find(nums[i]) != numsSet.end())
return true;
numsSet.insert(nums[i]);
if (i - k >= 0)
numsSet.erase(nums[i - k]);
}
return false;
}
};