Problem Statement

Given an array of numbers sorted in non-decreasing order, remove the duplicates in place so that each distinct value appears only once, keeping the values in sorted order at the front of the array. You may not use any extra space, so the solution must use constant extra space, O(1).

Return k, the number of distinct values. What the array holds beyond the first k positions does not matter and is not checked.

Example 1:

Input: [2, 3, 3, 3, 6, 9, 9]
Output: 4
Explanation: There are four distinct values, so the first four elements become [2, 3, 6, 9]. Whatever sits beyond position 4 is ignored.

Example 2:

Input: [2, 2, 2, 11]
Output: 2
Explanation: There are two distinct values, so the first two elements become [2, 11]. Whatever sits beyond position 2 is ignored.

Constraints:

• 1 <= nums.length <= 3 * 10⁴
• -100 <= nums[i] <= 100
• nums is sorted in non-decreasing order.

Try it yourself

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