[LeetCode][JavaScript]Median of Two Sorted Arrays

Median of Two Sorted Arrays 

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)).

https://leetcode.com/problems/median-of-two-sorted-arrays/

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给定两个排序过的数组，取这两个数组合并后的中位数。

如果是奇数长度，中位数就是中间的数；如果是偶数长度，中位数是中间两个数的平均数。

难点是题目要求复杂度是O(m+n)。

我的解法是先算出两个数组的总长度，然后循环从排序过的两个数组中取比较小的那个，统计长度，当长度等于总长度的一半时，根据奇数和偶数两种情况得到结果。

/**
 * @param {number[]} nums1
 * @param {number[]} nums2
 * @return {number}
 */
var findMedianSortedArrays = function(nums1, nums2) {
    var i = 0, j = 0, count = 0, middleLeft = -1;
    var len = nums1.length + nums2.length;
    while(i < nums1.length || j < nums2.length){
        var curr = 0;
        if(nums2[j] === undefined || nums1[i] <= nums2[j]){
            curr = nums1[i];
        }else if(nums1[i] === undefined || nums1[i] > nums2[j]){
            curr = nums2[j];
        }
        count++;
        if(len % 2 !== 0){
            if(count === (len - 1) / 2 + 1){
                return curr;
            }
        }else{
            if(count === len / 2){
                middleLeft = curr;
            }else if(count === (len / 2 + 1) && middleLeft !== -1){
                return (curr + middleLeft) / 2;
            }
        }

        if(nums2[j] === undefined || nums1[i] <= nums2[j]){
            i++;
        }else if(nums1[i] === undefined || nums1[i] > nums2[j]){
            j++;
        }
    }
    return 0;
};