48-Merge Sorted Array

$88. Merge Sorted Array My Submissions QuestionEditorial Solution
Total Accepted: 98885 Total Submissions: 329052 Difficulty: Easy
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.

思路：本题难度系数easy，虽然简单
但是要考虑到不使用额外空间以及边界的判定简便，代码简短还是不容易的
看了别人的，写得比我的短，于是又实现了一遍

有时候逆向思维很重要，要把所有元素依次放入nums1，开始难免陷入常规思维，从小到大。。。，但是你换个思路想想既然是有序，可以从大到小，所有元素的个数又是知道的，从末尾开始，始终都能保持nums1的元素不被覆盖

class Solution {
public:
     void merge(vector<int>& nums1, int m, vector<int>& nums2, int n) {
        int ia=m-1,ib=n-1,icur = m+n-1;
        while(ia>=0&&ib>=0){
            nums1[icur--]=nums1[ia]>=nums2[ib]?nums1[ia--]:nums2[ib--];
         }
         while(ib>=0){
            nums1[icur--]=nums2[ib--];
        }
     }
};