88. Merge Sorted Array

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

Note:

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

Input:
nums1 = [1,2,3,0,0,0], m = 3
nums2 = [2,5,6], n = 3

Output: [1,2,2,3,5,6]

【Idea】
简单粗暴，先把nums2的元素全赋值进来，然后排序；

方法二：
nums1的最后n个元素一定为0，从两个list的最末尾一同向前遍历，并比较两数的大小，将较大的一个赋值到nums1遍历的当前位置
trick：
在遍历nums1时，由m到当前遍历下标的map为: m+n-1

【Solution】

# 解法一
class Solution:
    def merge(self, nums1: List[int], m: int, nums2: List[int], n: int) -> None:
        """
        Do not return anything, modify nums1 in-place instead.
        """
        j = 0
        for i in range(m, len(nums1)):
            nums1[i] = nums2[j]
            j += 1
        nums1.sort()

# 解法二
class Solution:
  def merge(self, nums1, m, nums2, n):
          while m > 0 and n > 0:
              if nums1[m-1] >= nums2[n-1]:
                  nums1[m+n-1] = nums1[m-1]
                  m -= 1
              else:
                  nums1[m+n-1] = nums2[n-1]
                  n -= 1
          if n > 0:
              nums1[:n] = nums2[:n]