【Leetcode】Remove Duplicates from Sorted Array II

Follow up for "Remove Duplicates":
What if duplicates are allowed at most twice?

For example,
Given sorted array A = [1,1,1,2,2,3],

Your function should return length = 5, and A is now [1,1,2,2,3].

 

双指针的思路，但是这里容许两个重复，所以判断条件修改一下。

 

1st （5 tries）

class Solution 
{
public:
    int removeDuplicates(int A[], int n) 
    {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        int i,j,k,count;
        for(i = 0;i < n;++i)
        {
            count = 0;
            int tmp = A[i];
            j = i+2;
            while(j < n&&A[j] == tmp)
            {
                j++;
                count++;
            }
            if(count == 0)
                ;
            else
            {
                for( k = j; k < n;++k)
                {
                    A[k-count] = A[k];
                }
            }
            n -= count;
        }
        return n;
    }
};

　　

2nd（3 tries）

class Solution {
public:
    int removeDuplicates(int A[], int n) {
        int start = 0;
        for(int i = 0;i < n;i++) {
            if(i == 0 || i == 1) {
                A[start++] = A[i];
            }
            else {
                //using start
                if(A[i] == A[start-2]) {
                    
                }
                else {
                    A[start++] = A[i];
                }
            }
        }
        return start;
    }
};