[Leetcode] 26 Remove Duplicates from Sorted Array

Posted 2020-10-06 fengzw

原题地址：
https://leetcode.com/problems/remove-duplicates-from-sorted-array/description/

 

题目：

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 in place with constant memory.

For example,
Given input array 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.

 

解法：

先用一个变量记录下每次第一次出现的值，在循环中，每遇到一个大小相同的元素，直接删掉；当大小不等的时候，说明一个新的值已经出现了，就用变量记录下这个新的值的大小。以此类推，直至循环结束。时间复杂度为O(n)。代码如下：

class Solution {
public:
    int removeDuplicates(vector<int>& nums) {
        if (nums.size() == 0) {
            return 0;
        }
        vector<int>::iterator iter = nums.begin();
        int first = *iter;
        iter++;
        for (; iter != nums.end();) {
            if (*iter == first) {
                iter = nums.erase(iter);
            }
            else {
                first = *iter;
                iter++;
            }
        }
        return nums.size(); 
    }
};

于我而言，这题的难度在于把C++的知识都忘掉了，迭代器怎么用都忘了。罪过，罪过。