每日一题_leetcode：day6

# 方法一：偷懒版，使用内置函数sorted
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.
        """
        if m == 0 or n == 0:
            nums1[:] = nums2 if m == 0 else nums1
        else:
            nums1[m:m+n] = nums2
            nums1[:] = sorted(nums1)
			
# 逆向双指针
#（leetcode题解）
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.
        """
        p1, p2 = m - 1, n - 1
        tail = m + n - 1
        while p1 >= 0 or p2 >= 0:
            if p1 == -1:
                nums1[tail] = nums2[p2]
                p2 -= 1
            elif p2 == -1:
                nums1[tail] = nums1[p1]
                p1 -= 1
            elif nums1[p1] > nums2[p2]:
                nums1[tail] = nums1[p1]
                p1 -= 1
            else:
                nums1[tail] = nums2[p2]
                p2 -= 1
            tail -= 1
# 自写
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.
        """
        p1, p2 = m - 1, n - 1
        tail = m + n - 1
        while p1 >= 0 and p2 >= 0:
            while p2 >= 0 and nums2[p2] >= nums1[p1]:
                nums1[tail] = nums2[p2]
                p2 -= 1
                tail -= 1
            nums1[tail] = nums1[p1]
            p1 -= 1
            tail -= 1
        while p1 >=0 and tail >=0:
            nums1[tail] = nums1[p1]
            p1-=1
            tail-=1
        while p2 >= 0 and tail >=0:
            nums1[tail] = nums2[p2]
            p2-=1
            tail-=1
# 性能略逊色于leetcode版双指针