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LeetCode 88. Merge Sorted Array

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题目

原题在此
Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array.

The number of elements initialized in nums1 and nums2 are m and n respectively. You may assume that nums1 has enough space (size that is equal to m + n) to hold additional elements from nums2.

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]

Example 2:
Input: nums1 = [1], m = 1, nums2 = [], n = 0
Output: [1]

Constraints:

  • $0 <= n, m <= 200$
  • $1 <= n + m <= 200$
  • $nums_1.length == m + n$
  • $nums_2.length == n$
  • $-10^9 <= nums_1[i], nums_2[i] <= 10^9$

解析

根据题意, arr1足够大, 所以从arr1[m+n]开始倒着依次写入较大的数既可.

代码

C++

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class Solution {
public:
    void merge(vector<int>& a, int m, vector<int>& b, int n) {
        while(n) a[m + n] = (m > 0 && a[m - 1] > b[n - 1])? a[--m] : b[--n];
    }
};

Golang

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