LeetCode-026 Remove Duplicates from Sorted Array

Description

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.

Analyse

题意为去除一个有序数组中的重复的值，要求空间复杂度为常数级。既然要求复杂度为常数级，那么就是说，整个操作都是在原数组内完成的，所以我们只需要将不重复的元素提前到前面来就行，也是一道基础的题。

Code

class Solution {
public:
int removeDuplicates(vector<int>& nums) {
int count=0;
for (int i=1;i<nums.size();i++) {
if (nums[i]==nums[i-1]) count++;
else nums[i-count] = nums[i];
}
return nums.size()-count;
}
};