<p>Given an integer array <code>nums</code>, return <code>true</code> if any value appears <strong>at least twice</strong> in the array, and return <code>false</code> if every element is distinct.</p>

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

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">nums = [1,2,3,1]</span></p>

<p><strong>Output:</strong> <span class="example-io">true</span></p>

<p><strong>Explanation:</strong></p>

<p>The element 1 occurs at the indices 0 and 3.</p>
</div>

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

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">nums = [1,2,3,4]</span></p>

<p><strong>Output:</strong> <span class="example-io">false</span></p>

<p><strong>Explanation:</strong></p>

<p>All elements are distinct.</p>
</div>

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

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">nums = [1,1,1,3,3,4,3,2,4,2]</span></p>

<p><strong>Output:</strong> <span class="example-io">true</span></p>
</div>

<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>
</ul>

class Solution {
public:
    bool containsDuplicate(vector<int>& nums) {
         int i = 0, j = i + 1, k = 0;
    vector<int> arr(nums.size(), 0);
    sort(nums.begin(), nums.end());

    while (i < nums.size()) {
        if (j >= nums.size() || nums[i] != nums[j]) {
            arr[k++] = 0;
            i = j;
            j = j + 1;
        } else {
            arr[k++] = 1;
            j++;
            i = j;
            j = j + 1;
        }
    }

    for (int m = 0; m < k; m++) {
        if (arr[m] == 1) {
            return true;
        }
    }
    return false;
    }
};
63415