leetcode 29: Merge Sorted Array

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.

class Solution {
public:
    void merge(int A[], int m, int B[], int n) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if(n<1) return;
        
        int k = m+n-1;
        int i = m-1;
        int j = n-1;
        
        while( i>=0 && j>=0 ) {
            A[k--] = A[i] > B[j] ? A[i--] : B[j--];
        }
        
        while( j>=0 ) A[k--] = B[j--]; 
    }
};