[LeetCode29]Merge Sorted Array

题目来源：https://leetcode.com/problems/merge-sorted-array/

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 nums1and nums2 are m and n respectively.

考虑从后往前比较，这样就不会产生需要数据后移的问题了。时间复杂度O(n+m)

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