1. 题目

Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array.

Note:
You may assume that nums1 has enough space (size that is greater or equal to m + n) to hold additional elements from nums2. The number of elements initialized in nums1 and nums2 are m and n respectively.

2. 思路

从后往前，每次比较的大值直接填充到尾部的头上。
只需要遍历一次即可。

居然写了如此无聊的一个题目。。。。

3. 代码

class Solution {
public:
    void merge(vector<int>& nums1, int m, vector<int>& nums2, int n) {
        nums1.resize(m+n);
        int i = m-1;
        int j = n-1;
        int k = m+n-1;
        while (k >= 0) {
            if (i < 0) {
                nums1[k] = nums2[j--];
            } else if (j < 0) {
                break;
            } else if (nums1[i] > nums2[j]) {
                nums1[k] = nums1[i--];
            } else {
                nums1[k] = nums2[j--];
            }
            k--;
        }
    }
};