<p>Given an integer array <code>nums</code> and an integer <code>k</code>, return <code>true</code> <em>if there are two <strong>distinct indices</strong> </em><code>i</code><em> and </em><code>j</code><em> in the array such that </em><code>nums[i] == nums[j]</code><em> and </em><code>abs(i - j) &lt;= k</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> nums = [1,2,3,1], k = 3
<strong>Output:</strong> true
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> nums = [1,0,1,1], k = 1
<strong>Output:</strong> true
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> nums = [1,2,3,1,2,3], k = 2
<strong>Output:</strong> false
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
	<li><code>-10<sup>9</sup> &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
	<li><code>0 &lt;= k &lt;= 10<sup>5</sup></code></li>
</ul>

class Solution {
public:
    bool containsNearbyDuplicate(vector<int>& nums, int k) {
        int N = (int)nums.size();
        vector<int> ids(N);
        for(int i = 0; i < N; i++) {
            ids[i] = i;
        }
        sort(ids.begin(), ids.end(), [&nums](int a, int b) {
            if(nums[a] < nums[b]) {
                return true;
            }
            if(nums[a] == nums[b]) {
                return a < b;
            }
            return false;
        });
        for(int i = 1; i < N; i++) {
            if(nums[ids[i]] == nums[ids[i-1]] && abs(ids[i] - ids[i-1]) <= k) {
                return true;
            }
        }
        return false;
    }
};
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