154 Find Minimum in Rotated Sorted Array II

154. Find Minimum in Rotated Sorted Array II

1. Question

Follow upfor "Find Minimum in Rotated Sorted Array": What if duplicates are allowed?

Would this affect the run-time complexity? How and why?

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

(i.e.,0 1 2 4 5 6 7might become4 5 6 7 0 1 2).

Find the minimum element.

The array may contain duplicates.

2. Implementation

(1) Binary Search

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

        while (start + 1 < end) {
            mid = start + (end - start) / 2;

            if (nums[mid] > nums[end]) {
                start = mid + 1;
            }
            else if (nums[mid] < nums[end]) {
                end = mid;
            }
            else {
                --end;
            }
        }
        return nums[start] < nums[end] ? nums[start] : nums[end];
    }
}

3. Time & Space Complexity

时间复杂度最坏可以是O(n), 平均是log(n), 空间复杂度O(1)