Merge Sorted Array

题目链接https://leetcode.com/problems/merge-sorted-array/

这道题是merge sort中merge的过程，有一个trick是从后往前merge，这样可以避免多余的数组操作

class Solution {
public:
    void merge(int A[], int m, int B[], int n) {
        int i = m - 1, j = n - 1;
        int len = m + n - 1;
        while(i >= 0 && j >= 0) {
            if(A[i] > B[j]) {
                A[len] = A[i];
                i--;
            }
            else {
                A[len] = B[j];
                j--;
            }
            len--;
        }
        while(i >= 0) {
            A[len] = A[i];
            i--;
            len--;
        }
        while(j >= 0) {
            A[len] = B[j];
            j--;
            len--;
        }
    }
};