LeetCode OJ 4. 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)).
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
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【题目分析】
给定两个升序排列的整数数组,找到这两个数组所有元素的中位数。
【思路】
【java代码】
1 public class Solution { 2 public double findMedianSortedArrays(int[] nums1, int[] nums2) { 3 int[] A = nums1, B = nums2; 4 int m = nums1.length, n = nums2.length; 5 6 if(m > n){ 7 A = nums2; B = nums1; 8 m = nums2.length; n = nums1.length; 9 } 10 11 if(n == 0) return 0; 12 13 int mini = 0, maxi = m; 14 int i = 0, j = 0; 15 int maxofleft, minofright = 0; 16 17 while(mini <= maxi){ 18 i = (maxi - mini)/2 + mini; 19 j = (m + n + 1)/2 - i; 20 if(j > 0 && i < m && B[j-1] > A[i]){ 21 mini = i + 1; 22 } //i is too small 23 else if(i > 0 && j < n && A[i-1] > B[j]){ 24 maxi = i - 1; 25 } //i is too big 26 else{ 27 if(i == 0) maxofleft = B[j-1]; 28 else if(j == 0) maxofleft = A[i-1]; 29 else maxofleft = Math.max(A[i-1], B[j-1]); 30 31 if((m + n)%2 == 1) return maxofleft; 32 33 if(i == m) minofright = B[j]; 34 else if(j == n) minofright = A[i]; 35 else minofright = Math.min(B[j], A[i]); 36 37 return (double)(maxofleft + minofright) / 2.0; 38 } 39 } 40 return 0; 41 } 42 }