LeetCode – Remove Duplicates from Sorted Array (Java)

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于 2014-05-21 07:50:57 发布

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本文介绍了一种在不使用额外空间的情况下去除有序数组中重复元素的方法，并保持每个元素只出现一次。通过一次遍历和两个指针实现了原地修改数组并返回新长度的功能。

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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 A = [1,1,2],

Your function should return length = 2, and A is now [1,2].

Thoughts

The problem is pretty straightforward. It returns the length of array with unique elements, but the original array need to be changed also. This problem should be reviewed with Remove Duplicates from Sorted Array II.

Java Solution

public class Solution {
    public int removeDuplicates(int[] A) {
        if(A.length < 2)
            return A.length;
 
        int j = 0;
        int i = 1;
 
        while(i < A.length){
            if(A[i] == A[j]){
                i++;
            }else{
                A[++j] = A[i++];
            }    
        }
 
        return j+1;
    }
}