Leetcode--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 A = [1,1,2],

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

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 Array Two Pointers

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class Solution {
public:
    int removeDuplicates(int A[], int n) {
        //Time Limit Exceeded
        /*for(int i=1;i<n;i++)
        {
            if(i>0&&A[i]==A[i-1]){
                for(int j=i;j<n;j++)
                    A[j-1]=A[j];
                n--;
            }
        }
    
        return n;*/
        
        
        //AC
        for(int i=n-1;i>=0;i--)
        {
            if(i>0&&A[i]==A[i-1])
            {
                for(int j=i;j<n;j++)
                    A[j-1]=A[j];
                n--;
            }
        }
        return n;
            
    }
};

O（n）的解法參見：點擊打開https://oj.leetcode.com/discuss/10314/my-solution-time-o-n-space-o-1鏈接

int removeDuplicates(int A[], int n) {
        if(n < 2) return n;
        int id = 1;
        for(int i = 1; i < n; ++i) 
            if(A[i] != A[i-1]) A[id++] = A[i];
        return id;
    }