题目：

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.

刚开始根据归并排序写的多了一个中间数组

void MergeSortArr(int arrA[],int lA,int arrB[],int lB){
	int *trr = new int[lA+lB];
	int i = 0;
	int j = 0;
	int k = 0;
	while(i < lA && j < lB)
	{
		if(arrA[i] <= arrB[j])
			trr[k++] = arrA[i++];
		else
			trr[k++] = arrB[j++];
	}
	while(i < lA)
		trr[k++] = arrA[i++];
	while(j < lB)
		trr[k++] = arrB[j++];
	for(i = 0;i<k;++i)
	{
		arrA[i] = trr[i];
	}
	delete[] trr;
}

参考别人的写的版本从A的后面开始排序

void MergeSortArr1(int arrA[],int lA,int arrB[],int lB){
	int *trr = new int[lA+lB];
	int i = lA- 1;
	int j = lB- 1;
	int k = lA + lB - 1;
	while (i >= 0 && j >= 0)
	{
		if(arrA[i] >= arrB[j])
			arrA[k--] = arrA[i--];
		else
			arrA[k--] = arrB[j--];
	}
	while(i >= 0)
		arrA[k--] = arrA[i--];
	while(j >= 0)
		arrA[k--] = arrB[j--];

}

LeetCode (1) Merge Sorted Array