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Editor to share with you how to solve the problem of merging two ordered arrays in leetcode, I believe most people do not know much about it, so share this article for your reference. I hope you will gain a lot after reading this article. Let's learn about it together.

Topic link

Https://leetcode-cn.com/problems/merge-sorted-array/

Topic description

Given two ordered integer arrays nums1 and nums2, merge nums2 into nums1 so that num1 becomes an ordered array.

Description:

The number of elements initializing nums1 and nums2 is m and n, respectively.

You can assume that nums1 has enough space (the space size is greater than or equal to m + n) to hold the elements in nums2.

Example:

Enter:

Nums1 = [1, 2, 3, 0, 0, 0], m = 3

Nums2 = [2, 5, 5, 6], n = 3

Output: [1, 2, 2, 2, 3, 5, 6]

The idea of solving the problem

Tags: traversing the array from back to front

Because the space of the nums1 is concentrated at the back, it is better to process the sorted data from back to front, saving space and filling in values while traversing

Set the pointers len1 and len2 to point to the numeric tail of nums1 and nums2 respectively, compare the traversal starting from the tail value, and set the pointer len to the end of nums1. After each traversal compares the value, fill it.

When len1= 0 & & len2 > = 0) {

/ / Note-- the symbol comes after, indicating that the calculation is performed first and then minus 1, which shortens the code.

Nums1 [len--] = nums1 [len1] > nums2 [len2]? Nums1 [len1--]: nums2 [len2--]

}

/ / means to copy the nums2 array to the nums1 array starting from the subscript 0 position, starting from the subscript 0 position with a length of len2+1

System.arraycopy (nums2, 0, nums1, 0, len2 + 1)

}

}

JavaScript version

/ * *

* @ param {number []} nums1

* @ param {number} m

* @ param {number []} nums2

* @ param {number} n

* @ return {void} Do not return anything, modify nums1 in-place instead.

, /

Var merge = function (nums1, m, nums2, n) {

Let len1 = m-1

Let len2 = n-1

Let len = m + n-1

While (len1 > = 0 & & len2 > = 0) {

/ / Note-- the symbol comes after, indicating that the calculation is performed first and then minus 1, which shortens the code.

Nums1 [len--] = nums1 [len1] > nums2 [len2]? Nums1 [len1--]: nums2 [len2--]

}

Function arrayCopy (src, srcIndex, dest, destIndex, length) {

Dest.splice (destIndex, length,... src.slice (srcIndex, srcIndex + length))

}

/ / means to copy the nums2 array to the nums1 array starting from the subscript 0 position, starting from the subscript 0 position with a length of len2+1

ArrayCopy (nums2, 0, nums1, 0, len2 + 1)

}

Drawing and interpretation

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