33. Search in Rotated Sorted Array.cpp

/*
Link: https://leetcode.com/problems/search-in-rotated-sorted-array/

Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand.

(i.e., [0,1,2,4,5,6,7] might become [4,5,6,7,0,1,2]).

You are given a target value to search. If found in the array return its index, otherwise return -1.

You may assume no duplicate exists in the array.

Your algorithm's runtime complexity must be in the order of O(log n).

Example 1:

Input: nums = [4,5,6,7,0,1,2], target = 0
Output: 4
Example 2:

Input: nums = [4,5,6,7,0,1,2], target = 3
Output: -1
*/

// Solution

/*
TC = O(log n)
SC = O(1)
*/

class Solution {
public:
    int search(vector<int>& nums, int target) {
        int low = 0;
        int high = nums.size() - 1;
        
        while (low <= high) {
            int mid = low + (high - low) / 2;
            
            if (nums[mid] == target)
                return mid;
            
            else if (nums[mid] >= nums[high]) {
                if (target < nums[mid] && target >= nums[low])
                    high = mid - 1;
                else
                    low = mid + 1;
            }
            
            else if (nums[mid] < nums[high]) {
                if (target > nums[mid] && target <= nums[high])
                    low = mid + 1;
                else
                    high = mid - 1;
            }
        }
        return -1;
    }
};