C++代码

class Solution {
 public:
  static int removeDuplicates(vector<int> &nums) {
    if (nums.empty()) {
      return 0;
    }
    const int n = static_cast<int>(nums.size());
    int i = 0;
    for (int j = 1; j < n; ++j) {
      if (nums[i] != nums[j]) {
        ++i;
        nums[i] = nums[j];
      }
    }
    return ++i;
  }
};

Java代码

class Solution {
  public static int removeDuplicates(int[] nums) {
    if (nums.length == 0) {
      return 0;
    }
    int i = 0;
    for (int j = 1; j < nums.length; ++j) {
      if (nums[i] != nums[j]) {
        ++i;
        nums[i] = nums[j];
      }
    }
    return ++i;
  }
}

Python3代码

class Solution:
  def removeDuplicates(self, nums: list) -> int:
    n = len(nums)
    if n == 0:
      return 0
    i = 0
    for j in range(1, n):
      if nums[i] != nums[j]:
        i += 1
        nums[i] = nums[j]
    return i + 1

Go代码

func removeDuplicates(nums []int) int {
    n := len(nums)
    if n == 0 {
        return 0
    }
    i := 0
    for j := 1; j < n; j++ {
        if nums[i] != nums[j] {
            i++
            nums[i] = nums[j]
        }
    }
    i++
    return i
}