leetcode26

public class Solution {
    public int RemoveDuplicates(int[] nums) {
        var len = nums.Length;
            if (len == 0)
            {
                return 0;
            }
            else
            {
                var pre = nums[0];
                var diffindex = 0;
                for (int i = 1; i < nums.Length; i++)
                {
                    if (pre != nums[i])
                    {
                        nums[++diffindex] = nums[i];
                        pre = nums[i];
                    }
                }
                return diffindex + 1;
            }
    }
}

python实现如下：

class Solution:
    def removeDuplicates(self, nums: List[int]) -> int:
        s = set()
        n = len(nums)
        count = 0
        i,j = 0,0
        while i < n:
            if len(s) == 0 or nums[i] not in s:
                s.add(nums[i])
                nums[j] = nums[i]
                i += 1
                j += 1
                count += 1
            else:
                i += 1
        return count

不实用额外的空间，实现如下：

class Solution:
    def removeDuplicates(self, nums: 'List[int]') -> int:
        n = len(nums)
        i = 0
        j = i + 1
        count = 0
        while i < n:
            while j < n and nums[i] == nums[j]:
                j += 1
            count += 1
            if i + 1 < n and j < n:
                nums[i+1] = nums[j]
                i += 1
            else:
                return count
        return count