[LeetCode]第三十一题 :两个排序数组的中间值

题目描述:(困难难度)

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)).

Example 1:
nums1 = [1, 3]
nums2 = [2]

The median is 2.0
Example 2:
nums1 = [1, 2]
nums2 = [3, 4]

The median is (2 + 3)/2 = 2.5

题目解释:

有长度为m的整形数组1和长度为n的整形数组2。找到这两个数组的中间值。总的运行时间复杂度应该是O(log(m+n))。

题目解法:

1.我的解法。我的解法比较笨,先合并两个数组,然后取中间的数,最后返回值(其实没有必要全部合并,只需要查到相应的位置就可以了,后续的操作没有任何必要,当然啦,这两种的时间复杂度都是O(m+n),没有达到要求)。代码如下:

class Solution {
    public double findMedianSortedArrays(int[] nums1, int[] nums2) {
        int length = nums1.length + nums2.length;
        int[] temp = new int[length];
        int work1 = 0;
        int work2 = 0;
        for(int i = 0; i < length ; i++) {
            if(work1 < nums1.length && work2 < nums2.length) {
                if(nums1[work1] < nums2[work2]) {
                    temp[i] = nums1[work1];
                    work1 ++;
                } else {
                    temp[i] = nums2[work2];
                    work2 ++;
                }
            } else if(work1 >= nums1.length && work2 < nums2.length) {
                temp[i] = nums2[work2];
                work2 ++;
            } else if(work1 < nums1.length && work2 >= nums2.length) {
                temp[i] = nums1[work1];
                work1 ++;
            }
        }
        if(length % 2 == 1) {
            return Double.valueOf(temp[length / 2]);
        } else {
            return (temp[length / 2] + temp[length / 2 - 1]) / 2.0;
        }
    }
}

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