LeetCode & Q26-Remove Duplicates from Sorted Array-Easy

Descriptions:

Given a sorted array, remove the duplicates in place such that each element appears 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 't matter what you leave beyond the new length.

I have always had problems with what I wrote... I used a HashSet collection and have not studied this type. The output result of [1,1,2] is always [1,1]

(Write it down in a notebook to study HashSet)

<code class="sourceCode java"><span class="kw">import java.util.HashSet;</span>

<span class="kw">import java.util.Set;</span>

<span class="kw">public</span> <span class="kw">class</span> Solution {

    <span class="kw">public</span> <span class="dt">static</span> <span class="dt">int</span> <span class="fu">removeDuplicates</span>(<span class="dt">int</span>[] nums) {

        Set<Integer> tempSet = <span class="kw">new</span> HashSet<>();

        <span class="kw">for</span>(<span class="dt">int</span> i = <span class="dv">0</span>; i < nums.<span class="fu">length</span>; i++) {

            Integer wrap = Integer.<span class="fu">valueOf</span>(nums[i]);

            tempSet.<span class="fu">add</span>(wrap);

        }

        <span class="kw">return</span> tempSet.<span class="fu">size</span>();

    }

}</code>

The following are excellent answers

Solutions:

<code class="sourceCode java"><span class="kw">public</span> <span class="kw">class</span> Solution {

    <span class="kw">public</span> <span class="dt">static</span> <span class="dt">int</span> <span class="fu">removeDuplicates</span>(<span class="dt">int</span>[] nums) {

        <span class="dt">int</span> j = <span class="dv">0</span>;

        <span class="kw">for</span>(<span class="dt">int</span> i = <span class="dv">0</span>; i < nums.<span class="fu">length</span>; i++) {

            <span class="kw">if</span>(nums[i] != nums[j]) {

                nums[++j] = nums[i];

            }

        }

        <span class="kw">return</span> ++j;

    }

}</code>

There are two points to note:

1. Because there may be multiple duplicates, equality cannot be used as the judgment condition
2. Pay attention to the difference between j++ and ++j. The usage here is very clever and necessary!

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