LeetCode 88. Merge Sorted Array

Problem Statement

(Source) 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.

Tags: Array, Two Pointers.

Solution

Use Two Pointers to greedily choose the larger one from end s of the two array, and update the next insertion position by one cell.

class Solution(object):    def merge(self, nums1, m, nums2, n):        """        :type nums1: List[int]        :type m: int        :type nums2: List[int]        :type n: int        :rtype: void Do not return anything, modify nums1 in-place instead.        """        pos = m + n - 1        i, j = m - 1, n - 1        while j >= 0:            if i >= 0 and nums1[i] > nums2[j]:                nums1[pos] = nums1[i]                i -= 1            else:                nums1[pos] = nums2[j]                j -= 1            pos -= 1

Complexity Analysis:

• Time Complexity: O(m+n).
• Space Complexity: O(1).