合并有序数组

有两个排序数组A1和A2，内存在A1的末尾有足够多的空余空间容纳A2，实现一个函数，把A2插入到A1，并且是有序的。 

分析:从尾到头比较A1和A2的数字，并把较大的数字复制到合适的位置。

#include <stdio.h>
#include "stdafx.h"

void DisplayArray(int* pArray, int nLength)
{
    for(int i = 0 ; i < nLength; ++i)
        printf("%d\t", pArray[i]);
    printf("\n");
}

int *MergeArray(int* pArray1, int nLength1, int* pArray2, int nLength2, int* pArray3)
{
    if(pArray1 == NULL || pArray2 == NULL)
        return NULL;

    int k = nLength1 + nLength2 -1;
    int i = nLength1 - 1;
    int j = nLength2 - 1;
    
    //先将array1复制到array3前面 
    for(int n = 0 ; n <= i; n ++)
        pArray3[n] = pArray1[n];
    
    
    //从后往前比较array1和array2 
    while(i >= 0 && j >=0)
    {
        if(pArray1[i] > pArray2[j])
            pArray3[k --] = pArray1[i --];
        else
            pArray3[k--] = pArray2[j--];
    }
    while(j >= 0)
        pArray3[k --] = pArray2[j --];

    return pArray3;
}

int main()
{
    int array1[] = {1,4,5,7};
    int length1 = sizeof(array1)/sizeof(int);
    printf("array1 is: ");
    DisplayArray(array1, length1);

    int array2[] = {2,3,6,8};
    int length2 = sizeof(array2)/sizeof(int);
    printf("array2 is: ");
    DisplayArray(array2, length2);

    int length3= length1 + length2;
    int array3[length3];

    int *pArray3 = MergeArray(array1,length1,array2,length2,array3);
    printf("Merge Array: \n");
    DisplayArray(pArray3, length3);

    return 0;
}