704-binary-search

Question

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

Given a sorted (in ascending order) integer array nums of n elements and a target value, write a function to search target in nums. If target exists, then return its index, otherwise return -1.

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

Note:

1. You may assume that all elements in nums are unique.
2. n will be in the range [1, 10000].
3. The value of each element in nums will be in the range [-9999, 9999].

Thought Process

1. Binary
   1. Time complexity O(logn)
   2. Space complexity O(1)

Solution

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

Additional