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.

结题分析：当时想的是从前往后比较，A[]>B[]，那么插入B[]，A[]再往后移位。复杂度是（n^2）

                 后面才发现，可以从后往前。思路

class Solution {
public:
    void merge(int A[], int m, int B[], int n) {
      int pointa = m-1;
      int pointb = n-1;

      for(int i = m+n-1; i >= 0; i--) {
         if(pointa == -1 )  A[i] = B[pointb--];
         else if(pointb == -1 )  A[i] = A[pointa--];
           else {
             if(A[pointa] > B[pointb])  A[i] = A[pointa--];
                else A[i] = B[pointb--];
             }
        }
      }

};

LeetCode-Merge Sorted Array