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 (size that is greater or equal to m + n) to hold additional elements from B. The number of elements initialized in A and B are m andn respectively.

// https://oj.leetcode.com/problems/merge-sorted-array/
// Author : Chao Zeng
// Date   : 2015-2-2

class Solution {
public:
    void merge(int A[], int m, int B[], int n) {
        int newlength = m + n - 1;
        int length1 = m - 1;
        int length2 = n - 1;
        //两个数组末尾开始比较
        while(length1 >= 0 && length2 >= 0){
            if (A[length1] > B[length2]){
                A[newlength] = A[length1];
                length1--;
            }
            else{
                A[newlength] = B[length2];
                length2--;
            }
            newlength--;
        }
        //如果数组B比数组A长
        while(length2 >= 0){
            A[newlength] = B[length2];
            length2--;
            newlength--;
        }
    }
};