leetcode4leetcode4

https://leetcode.com/problems/median-of-two-sorted-arrays/
这是一道水题,
两个有序列表求中位数.
思路很简单,先合并,再求中位数
合并的方式不是先随意合并,再排序,这样时间复杂度就变为了
O((n+m)log2(n+m)).
两列表有序,类似归并排序的合并方式,只需要O(n+m)时间

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
class Solution {
public double findMedianSortedArrays(int[] nums1, int[] nums2) {

int len1 = nums1.length;
int len2 = nums2.length;

int[] a = new int[len1+len2];
for (int i=0;i<len1+len2;i++){
a[i] = 0;
}

int i=0;int j=0;int k = 0;
while(i<len1 && j<len2){
if (nums1[i]<nums2[j]){
a[k] = nums1[i];
i++;
}else{
a[k] = nums2[j];
j++;
}
k++;
}

while (i<len1){
a[k] = nums1[i];
i++;
k++;
}
while (j<len2){
a[k] = nums2[j];
j++;
k++;
}

if ((len1+len2)%2==0){
int mid = (len1+len2)/2;
double p = (a[mid-1]+a[mid])/2.0;
return p;
}else{
int mid = (len1+len2)/2+1;
return a[mid-1];
}

}
}