remove duplicate of the sorted array

description:

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.

 

thoughts:

first we should juage if the array is empty, if true, we can just return length=0,and do not do anything special about the array.if not, then the length must >=1.we first record the nums[0]  as temp and  legnth = 1, then find the first different number with it,make the temp equal to it, and length++;end make the nums[length -1] = temp.do this operation untill you have scan all the value of the nums,then return length.

 

my code in java

package easy;

public class RemoveDuplicatesOfSortedArray {
    
    public int removeDuplicates(int[] nums){
        //if the nums is empty return length = 0
        int length = 0;
        if(nums.length>0){
            int temp = nums[0];
            length=1;
            for(int i = 0; i<nums.length;i++){
                if(temp != nums[i]){
                    //找到所有不一样的数
                    temp = nums[i];
                    length++;
                    //将所有不一样的数放在相应的位置
                    nums[length - 1] = temp;
                }
            }
        }
        
        return length;
    }
    
    public static void main(String[] args){
        RemoveDuplicatesOfSortedArray a = new RemoveDuplicatesOfSortedArray();
        int[] nums = new int[]{1,1,2};
        int length = a.removeDuplicates(nums);
        System.out.println(length);
    }

}