## 26. Remove Duplicates from Sorted Array

Given a sorted array, remove the duplicates in-place such that each element appear only once and return the new length.

Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.

Example:

```Given nums = [1,1,2],

Your function should return length = 2, with the first two elements of nums being 1 and 2 respectively.
It doesn't matter what you leave beyond the new length.
```

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## Solution

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#### Approach #1 (Two Pointers) [Accepted]

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Algorithm

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Since the array is already sorted, we can keep two pointers and , where is the slow-runner while is the fast-runner. As long as , we increment to skip the duplicate.

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When we encounter , the duplicate run has ended so we must copy its value to . is then incremented and we repeat the same process again until reaches the end of array.

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`public int removeDuplicates(int[] nums) {\n    if (nums.length == 0) return 0;\n    int i = 0;\n    for (int j = 1; j < nums.length; j++) {\n        if (nums[j] != nums[i]) {\n            i++;\n            nums[i] = nums[j];\n        }\n    }\n    return i + 1;\n}\n`
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Complexity analysis

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Time complextiy : .\nAssume that is the length of array. Each of and traverses at most steps.

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Space complexity : .

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