Merge Sorted Array [LeetCode]

Given two sorted integer arrays A and B, merge B into A as one sorted array.

Note:
You may assume that A has enough space to hold additional elements from B. The number of elements initialized in A and B are m and n respectively.

Summary: It's easy, but should be careful about corner cases, like m is 0, n is 0.

 1     void merge(int A[], int m, int B[], int n) {
 2         if(n == 0)
 3             return;
 4         if(m == 0) {
 5             memcpy(A, B, n * sizeof(B[0]));
 6             return;
 7         }
 8         int a = 0;
 9         int b = 0;
10         int a_idx = 0;
11         int new_len = m;
12         while(true) {
13             if(A[a] >= B[b]) {
14                 //insert B[b] before A[a]
15                 for(int i = new_len; i >= a + 1; i --) 
16                     A[i] = A[i - 1];
17                 A[a] = B[b];
18                 new_len ++;
19                 b ++;
20                 if(b >= n)
21                     break;
22                 a ++;
23             }else {
24                 if(a_idx >= m) {
25                     //copy rest B to tail of A
26                     memcpy(A + a, B + b, (n-b)*sizeof(A[0]));
27                     break;
28                 }
29                 a ++;
30                 a_idx ++;
31             }
32         }
33     }