159. Find Minimum in Rotated Sorted Array [LintCode]

Suppose a sorted array 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.

Notice

You may assume no duplicate exists in the array.

Example

Given[4, 5, 6, 7, 0, 1, 2]return0

public class Solution {
    /**
     * @param nums: a rotated sorted array
     * @return: the minimum number in the array
     */
    public int findMin(int[] nums) {
        // write your code here
        if (nums == null || nums.length == 0) {
            return -1;
        }
        int ref = nums[nums.length - 1];
        int left = 0;
        int right = nums.length - 1;
        while (left + 1 < right) {
            int mid = left + (right - left) / 2;
            if (nums[mid] > ref) {
                left = mid;
            } else {
                right = mid;
            }
        }
        if (nums[left] <= nums[right]) {
            return nums[left];
        }
        return nums[right];
    }
}