LeetCode Challenge #33. Search in Rotated Sorted Array

Day 23 of 100 Days LeetCode Challenge

LeetCode Challenge #33. Search in Rotated Sorted Array

There is an integer array nums sorted in ascending order (with distinct values).

Prior to being passed to your function, nums is possibly rotated at an unknown pivot index k (1 <= k < nums.length) such that the resulting array is [nums[k], nums[k+1], ..., nums[n-1], nums[0], nums[1], ..., nums[k-1]] (0-indexed). For example, [0,1,2,4,5,6,7] might be rotated at pivot index 3 and become [4,5,6,7,0,1,2].

Given the array nums after the possible rotation and an integer target, return the index of target if it is in nums, or -1 if it is not in nums.

You must write an algorithm with O(log n) runtime complexity.

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

Example 3:

Input: nums = [1], target = 0
Output: -1

Constraints:

1 <= nums.length <= 5000
-10⁴ <= nums[i] <= 10⁴
All values of nums are unique.
nums is an ascending array that is possibly rotated.
-10⁴ <= target <= 10⁴

Video Solution

Java Solution

				
					class Solution {
    public int search(int[] nums, int target) {
        int start = 0 ;
        int end = nums.length-1;

        while(start<=end){
            int mid = (start + end)/2;
            if(nums[mid]==target){
                return mid ;
            }else if (nums[start]<=nums[mid]){ // first part is sorted 

            if(target>=nums[start] && target<nums[mid]){
                end = mid-1;
            }else{
                start = mid+1;
            }
            
            }else{ // second part is sorted 
                if(target>nums[mid] && target<=nums[end]){
                    start = mid+1;
                }else{
                    end = mid-1;
                }
            }
        }
        return -1 ;
    }
}

Day 23 of 100 Days LeetCode Challenge