LeetCode-88. Merge Sorted Array

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问题描述

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 :

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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.

Constraints:

  • nums1.length == m + n
  • nums2.length == n
  • 0 <= m, n <= 200
  • 1 <= m + n <= 200
  • -109 <= nums1[i], nums2[j] <= 109

解答

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/*
 * @Description: 88. Merge Sorted Array
 * @Author: libk
 * @Github: https://github.com/libk
 */
/**
 * @param {number[]} nums1
 * @param {number} m
 * @param {number[]} nums2
 * @param {number} n
 * @return {void} Do not return anything, modify nums1 in-place instead.
 */
const merge = function (nums1, m, nums2, n) {
  let p1 = m - 1
  let p2 = n - 1
  let tail = m + n - 1
  let cur

  while (p1 >= 0 || p2 >= 0) {
    if (p1 === -1) {
      cur = nums2[p2--]
    } else if (p2 === -1) {
      cur = nums1[p1--]
    } else if (nums1[p1] > nums2[p2]) {
      cur = nums1[p1--]
    } else {
      cur = nums2[p2--]
    }
    nums1[tail--] = cur
  }
}