[LeetCode] 88 | Merge Sorted Array | Python

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문제 링크: https://leetcode.com/problems/merge-sorted-array/

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문제

You are given two integer arrays nums1 and nums2, sorted in non-decreasing order, and two integers m and n, representing the number of elements in nums1 and nums2 respectively.

Merge nums1 and nums2 into a single array sorted in non-decreasing order.

The final sorted array should not be returned by the function, but instead be stored inside the array nums1. To accommodate this, nums1 has a length of m + n, where the first m elements denote the elements that should be merged, and the last n elements are set to 0 and should be ignored. nums2 has a length of n.

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조건

• nums1.length == m + n
• nums2.length == n
• 0 <= m, n <= 200
• 1 <= m + n <= 200
• $-10^9$ <= nums1[i], nums2[j] <= $10^9$

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내 풀이

nums1 array 뒤쪽이 0으로 채워져있다는 점을 기억하자.

앞에서부터 작은 숫자를 채우는 대신, 뒤에서부터 큰 숫자를 채운다고 생각한다.

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코드

class Solution:
    def merge(self, nums1: List[int], m: int, nums2: List[int], n: int) -> None:
        k = len(nums1)
        
        while m > 0 and n > 0:
            if nums1[m-1] > nums2[n-1]:
                nums1[k-1] = nums1[m-1]
                m -= 1
            else:
                nums1[k-1] = nums2[n-1]
                n -= 1
            k -= 1
            
        while n > 0:
            nums1[k-1] = nums2[n-1]
            k -= 1
            n -= 1