CODE 45: Merge Sorted Array

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.

public void merge(int A[], int m, int B[], int n) {
// Start typing your Java solution below
// DO NOT write main() function
if (null == B) {
return;
}
int[] insert = new int[n + 1];
insert[0] = -1;
int insertIndex = 1;
int lastJ = 0;
for (int i = 0, j = 0; j < m && i < n;) {
if (A[j] < B[i]) {
j++;
continue;
} else {
insert[insertIndex] = insert[insertIndex - 1] + j - lastJ + 1;
insertIndex++;
int k;
for (k = i + 1; k < n; k++) {
if (B[k] <= A[j]) {
insert[insertIndex] = insert[insertIndex - 1] + 1;
insertIndex++;
} else {
break;
}
}
i += k - i;
lastJ = j;
}
}
int moveStep = insertIndex - 1;
for (int i = m - 1; i >= 0; i--) {
if (insert[moveStep] != i + moveStep || moveStep == 0) {
A[i + moveStep] = A[i];
} else {
A[i + moveStep] = B[moveStep - 1];
i++;
moveStep--;
}
}
if (moveStep != 0) {
for (int i = 0; i < moveStep; i++) {
A[i] = B[i];
}
}
if (insertIndex - 1 < n) {
for (int i = m - 1 + insertIndex; i < m + n; i++) {
A[i] = B[i - m];
}
}
}