4. Median of Two Sorted Arrays
Overall
Difficulty: Hard
Link: https://leetcode.com/problems/median-of-two-sorted-arrays/
Introduction
Median of Two Sorted Arrays is a first Hard problem in Leetcode. It provided two arrays "nums1" and "nums2" and the program need to find the median of these two sorted arrays.
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The key point is combine these two arrays that can find a median of these two sorted arrays.
Problem Content
Given two sorted arrays nums1 and nums2 of size m and n respectively, return the median of the two sorted arrays.
The overall run time complexity should be O(log (m+n)).
Example 1:
Input: nums1 = [1,3], nums2 = [2] Output: 2.00000 Explanation: merged array = [1,2,3] and median is 2.
Example 2:
Input: nums1 = [1,2], nums2 = [3,4] Output: 2.50000 Explanation: merged array = [1,2,3,4] and median is (2 + 3) / 2 = 2.5.
Constraints:
nums1.length == m
nums2.length == n
0 <= m <= 1000
0 <= n <= 1000
1 <= m + n <= 2000
-106 <= nums1[i], nums2[i] <= 106
Concept
The problem is provide two array called "nums1" and "nums2" then the program need to return a median of these two sorted arrays.
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First, we use "nums1.concat(nums2)" to combine two array as "merged_array" and use "merged_array.sort((a, b)=> a - b)" to sort them by increase order.
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Then, if the length of "merged_array" is odd, it should return a number at middle point in the array("merged_array[(merged_array.length-1)/2]") as median. Otherwise return the average of two number at middle point in the array as median("merged_array[(merged_array.length-2)/2]+merged_array[(merged_array.length)/2])/2").
Solve(Javascript)
/**
* @param {number[]} nums1
* @param {number[]} nums2
* @return {number}
*/
var findMedianSortedArrays = function(nums1, nums2) {
let merged_array=nums1.concat(nums2);
merged_array.sort((a, b)=> a - b);
if(merged_array.length % 2==1){
return merged_array[(merged_array.length-1)/2];
}else{
return (merged_array[(merged_array.length-2)/2]+merged_array[(merged_array.length)/2])/2;
}
};