leetcode：Median of Two Sorted Arrays 【Java】

一、问题描述

There are two sorted arrays nums1 and nums2 of size m and n respectively. Find the median of the two sorted arrays. The overall run time complexity should be O(log (m+n)).

二、问题分析

合并两个有序数组（参考算法leetcode：Merge Sorted
Array 【Java】）后，寻找中位数。

三、算法代码

public class Solution {
    public double findMedianSortedArrays(int[] nums1, int[] nums2) {
        int [] mergedArray = merge(nums1, nums1.length, nums2, nums2.length);
        int len = mergedArray.length;

        double middle = 0.0;
        if(len % 2 == 0){
            middle = ((double)mergedArray[(len - 1) / 2] + (double)mergedArray[(len - 1) / 2 + 1]) / 2;
        }else{
            middle = (double)mergedArray[(len - 1) / 2];
        }
        return middle;
    }
    
    //合并两个有序数组
    public int[] merge(int[] nums1, int m, int[] nums2, int n) {
        int a_index = m - 1;
        int b_index = n - 1;
        int a_cur = m + n - 1;
        int [] result = new int[m + n];
        while(a_index >= 0 && b_index >= 0){
        	if(nums1[a_index] >= nums2[b_index]){
        		result[a_cur] = nums1[a_index];
        		a_cur--;
        		a_index--;
        	}else{
        		result[a_cur] = nums2[b_index];
        		a_cur--;
        		b_index--;
        	}
        }
        while(b_index >= 0){
        	result[a_cur] = nums2[b_index];
    		a_cur--;
    		b_index--;
        }
        while(a_index >= 0){
        	result[a_cur] = nums1[a_index];
    		a_cur--;
    		a_index--;
        }
        return result;
    }
}