[LeetCode] Remove Duplicates from Sorted Array & Remove Element

Remove Duplicates from Sorted Array

Remove Element

发现这两题性质差不多，于是就一起写了吧.

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 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.

• 题意：把一个有序数组去掉重复部分，返回不重复的个数.也就是stl中的unique.
• 解法：一直循环如果第i个和第i-1个不同，说明是应该保留的，如果相同的话，上一个就被保留了.

class Solution {
public:
    int removeElement(vector<int>& nums, int val) {
        int iResult = 0;
        for (int i = 0; i < (int)nums.size(); ++i) {
            if (nums[i] != val)
                nums[iResult++] = nums[i];
        }
        return iResult;
    }
};

Remove Element

Given an array and a value, remove all instances of that value in place and return the new length.

The order of elements can be changed. It doesn’t matter what you leave beyond the new length.

• 题意：给定数组和指定数字，把等于这个数字的数从数组中移除.
• 解法: 跟上一个差不多，循环，遇见不等于这个目标数字的，就保留.

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

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