# Contains Duplicate III Problem

## Description

LeetCode Problem 220.

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

Example 1:

``````1
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Input: nums = [1,2,3,1], k = 3, t = 0
Output: true
``````

Example 2:

``````1
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Input: nums = [1,0,1,1], k = 1, t = 2
Output: true
``````

Example 3:

``````1
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Input: nums = [1,5,9,1,5,9], k = 2, t = 3
Output: false
``````

Constraints:

• 1 <= nums.length <= 2 * 10^4
• -2^31 <= nums[i] <= 2^31 - 1
• 0 <= k <= 10^4
• 0 <= t <= 2^31 - 1

## Sample C++ Code

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bool containsNearbyAlmostDuplicate(vector<int>& nums, int k, int t) {
set<int> window; // set is ordered automatically

for (int i = 0; i < nums.size(); i++) {
if (i > k)
// keep the set contains nums i j at most k
window.erase(nums[i-k-1]);

// |x - nums[i]| <= t  ==> -t <= x - nums[i] <= t;
// x-nums[i] >= -t ==> x >= nums[i]-t
auto pos = window.lower_bound(nums[i] - t);

// x - nums[i] <= t ==> |x - nums[i]| <= t
if (pos != window.end() && *pos - nums[i] <= t)
return true;

window.insert(nums[i]);
}
return false;
}
``````