88. Merge Sorted Array

Easy

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.

Example 1:

Input: nums1 = [1,2,3,0,0,0], m = 3, nums2 = [2,5,6], n = 3
Output:
 [1,2,2,3,5,6]
Explanation:
 The arrays we are merging are [1,2,3] and [2,5,6].
The result of the merge is [1,2,2,3,5,6] with the underlined elements coming from nums1.

Example 2:

Input: nums1 = [1], m = 1, nums2 = [], n = 0
Output:
 [1]
Explanation:
 The arrays we are merging are [1] and [].
The result of the merge is [1].

Example 3:

Input: nums1 = [0], m = 0, nums2 = [1], n = 1
Output:
 [1]
Explanation:
 The arrays we are merging are [] and [1].
The result of the merge is [1].
Note that because m = 0, there are no elements in nums1. The 0 is only there to ensure the merge result can fit in nums1.

Constraints:

• nums1.length == m + n

• nums2.length == n

• 0 <= m, n <= 200

• 1 <= m + n <= 200

• -109 <= nums1[i], nums2[j] <= 109

解法

func merge(nums1 []int, m int, nums2 []int, n int) {
	for m > 0 && n > 0 {
		if nums1[m-1] >= nums2[n-1] {
			nums1[m+n-1] = nums1[m-1]
			m--
		} else {
			nums1[m+n-1] = nums2[n-1]
			n--
		}
	}
	if m == 0 {
		for n > 0 {
			nums1[n-1] = nums2[n-1]
			n--
		}
	}
}