LeetCode 从排序数组中删除重复项 26. Remove Duplicates from Sorted Array

墨蓝 2022-01-12 08:51 149阅读 0赞

Given a sorted array nums, 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 1:
    
    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 returned length.

Example 2:
    
    Given nums = [0,0,1,1,1,2,2,3,3,4],
    
    Your function should return length = 5, with the first five elements of nums being modified to 0, 1, 2, 3, and 4 respectively.
    
    It doesn't matter what values are set beyond the returned length.

题目给我们一个有序数组，返回这个有序数组中不重复的元素个数。  
可以使用一个指针 i 指向数组首个元素，使用另外一个指针 j 从剩下的数组开头开始遍历。

*  如果 nums\[j\] == nums\[i\] 则 j++ 什么都不做，继续向后遍历；
 *  如果 nums\[j\] != nums\[i\] 则 nums\[++i\] = nums\[j\]；
 *  最后 j 遍历完成后返回 i+1 则是不重复的元素个数。

class Solution { 
        public int removeDuplicates(int[] nums) { 
            if (nums.length == 0) return 0;
            int i = 0;
            for(int j = 1; j < nums.length; j++){ 
                if(nums[i] != nums[j]){ 
                    nums[++i] = nums[j];
                }
            }
            return i + 1;
        }
    }