*Binary Search

標籤：

For a given sorted array (ascending order) and a target number, find the first index of this number in O(log n) time complexity.

If the target number does not exist in the array, return -1.

 

Have you met this question in a real interview?

YesWhich company asked you this question? Airbnb Alibaba Amazon Apple Baidu Bloomberg Cisco Dropbox Ebay Facebook Google Hulu Intel Linkedin Microsoft NetEase Nvidia Oracle Pinterest Snapchat Tencent Twitter Uber Xiaomi Yahoo Yelp Zenefits Thanks for your feedback. Example

If the array is [1, 2, 3, 3, 4, 5, 10], for given target 3, return 2.

Challenge

If the count of numbers is bigger than 2^32, can your code work properly?

 

 

 

 

 

 

 1     public int binarySearch(int[] nums, int target)  2     { 3         //write your code here 4         if(nums.length==0)return -1; 5         int left = 0; 6         int right = nums.length-1; 7         while(left+1 <right) 8         { 9             int mid = (left + right) /2;10             if(target==nums[mid])11             {12                 right = mid;13             }14             15             if(target<nums[mid])16             {17                 right = mid-1;18             }19             if(target>nums[mid])20             {21                 left = mid+1;22             }23             24         }25         26         if(nums[left]==target) return left;27         if(nums[right]==target) return right;28         return -1;29     }

 

*Binary Search