Array / String#

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:

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

Example 2:

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

Example 3:

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

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class Solution:
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    def merge(self, nums1: List[int], m: int, nums2: List[int], n: int) -> None:
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        """
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        Do not return anything, modify nums1 in-place instead.
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        """
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        i, j, k = m - 1, n - 1, m + n - 1
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        while i >= 0 and j >= 0:
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            if nums1[i] <= nums2[j]:
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                nums1[k] = nums2[j]
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                j -= 1
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            else:
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                nums1[k] = nums1[i]
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                i -= 1
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            k -= 1
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        if j >= 0:
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            nums1[: k + 1] = nums2[: j + 1]
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class Solution {
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public:
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    void merge(vector<int>& nums1, int m, vector<int>& nums2, int n) {
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        int i = m - 1;
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        int j = n - 1;
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        int k = m + n - 1;
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        while (i >= 0 && j >= 0) {
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            if (nums1[i] <= nums2[j]) {
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                nums1[k--] = nums2[j--];
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            } else {
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                nums1[k--] = nums1[i--];
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            }
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        }
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        while (j >= 0) {
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            nums1[k--] = nums2[j--];
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        }
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    }
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};