LeetCode Online Judge 题目C# 练习 - 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].

 1         public static int RemoveDuplicatesfromSortedArrayII(int[] A)
 2         {
 3             int prev = A[0];
 4             int numtoremove = 0;
 5             int ret = A.Length;
 6 
 7             for (int i = 1; i < ret; i++)
 8             {
 9                 if (prev == A[i])
10                 {
11                     numtoremove++;
12                 }
13                 else
14                 {
15                     if (numtoremove > 1)
16                     {
17                         RemoveDuplicatesfromSortedArrayShiftLeft(A, ret, i, numtoremove - 1);
18                         ret -= numtoremove - 1;
19                         i -= numtoremove - 1;
20                     }
21                     prev = A[i];
22                     numtoremove = 0;
23                 }
24             }
25 
26             if (numtoremove > 1)
27             {
28                 ret -= numtoremove - 1;
29             }
30 
31             return ret;
32         }
33         
34         public static void RemoveDuplicatesfromSortedArrayShiftLeft(int[] A, int alength, int index, int n)
35         {
36             for (int i = index; i < alength; i++)
37             {
38                 A[i - n] = A[i];
39             }
40         }

代码分析：

　　也不难，少remove一个而已，但是要记得 prev = A[i], numtoremove = 0 在下一个不重复处就都需要做。 同样不能忘了最后一个数重复的corner case。