[LeetCode] 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 (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.

 

思路：从后往前复制，注意两个数组都为空或者其中一个数组为空的情况。

　　　时间复杂度O(n),空间复杂度O(1)

class Solution {
public:
    void merge(int A[], int m, int B[], int n) {
        if (n == 0)
            return;
        int index = m + n - 1;
        int ia = m - 1;
        int ib = n - 1;
        while (ia >=0 && ib >= 0) {
            A[index--] = A[ia] >= B[ib] ? A[ia--] : B[ib--];
        }
        while (ib >= 0) {
            A[index--] = B[ib--];
        }
    }
};