154. Find Minimum in Rotated Sorted Array II

Description

Suppose an array of length n sorted in ascending order is rotated between 1 and n times. For example, the array nums = [0,1,4,4,5,6,7] might become:

• [4,5,6,7,0,1,4] if it was rotated 4 times.
• [0,1,4,4,5,6,7] if it was rotated 7 times.

Notice that rotating an array [a[0], a[1], a[2], ..., a[n-1]] 1 time results in the array [a[n-1], a[0], a[1], a[2], ..., a[n-2]].

Given the sorted rotated array nums that may contain duplicates, return the minimum element of this array.

You must decrease the overall operation steps as much as possible.

 

Example 1:

Input: nums = [1,3,5]
Output: 1

Example 2:

Input: nums = [2,2,2,0,1]
Output: 0

 

Constraints:

• n == nums.length
• 1 <= n <= 5000
• -5000 <= nums[i] <= 5000
• nums is sorted and rotated between 1 and n times.

 

Follow up: This problem is similar to Find Minimum in Rotated Sorted Array, but nums may contain duplicates. Would this affect the runtime complexity? How and why?

 

 

Solutions

Solution: Binary Search

• Time complexity: O(n/2)
• Space complexity: O(1)

 

JavaScript

/**
 * @param {number[]} nums
 * @return {number}
 */
const findMin = function (nums) {
  let left = 0;
  let right = nums.length - 1;

  while (left < right) {
    const mid = Math.floor((left + right) / 2);

    if (nums[mid] === nums[left] && nums[mid] === nums[right]) {
      left += 1;
      right -= 1;
      continue;
    }
    nums[mid] <= nums[right] ? (right = mid) : (left = mid + 1);
  }
  return nums[left];
};