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].

分析：从第三个数开始，每个数都只和它前面第二个数相比较，如果不同的话，则在结果中添加该数；如果相同，则不处理。运行时间21ms

1 class Solution { 2 public: 3     int removeDuplicates(int A[], int n) { 4         if(n <= 2) return n; 5          6         int index = 2; 7         for(int i = 2; i < n; i++){ 8             if(A[i] != A[index-2]) A[index++] = A[i]; 9         }10         return index;11     }12 };