LeetCode - 704. Binary Search(Array, Binary Search)*

문제

Given an array of integers nums which is sorted in ascending order, and an integer target, write a function to search target in nums. If target exists, then return its index. Otherwise, return -1.
You must write an algorithm with O(log n) runtime complexity.

https://leetcode.com/problems/binary-search

Example 1:

Input: nums = [-1,0,3,5,9,12], target = 9
Output: 4
Explanation: 9 exists in nums and its index is 4

Example 2:

Input: nums = [-1,0,3,5,9,12], target = 2
Output: -1
Explanation: 2 does not exist in nums so return -1

풀이

class Solution {
    public int search(int[] nums, int target) {
    
        int start = 0;
        int end = nums.length -1;
        
        while(start<=end){
            int mid=(end+start)/2;
            if(nums[mid]==target) return mid;
            else if(nums[mid]<target) start = mid+1;
            else end=mid-1;    
        }
        return -1;
    }
}