Find Minimum in Rotated Sorted Array II

Description

Suppose a sorted array 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).

Find the minimum element.

Notice

The array may contain duplicates.

Example

Given [4,4,5,6,7,0,1,2] return 0.

Related problems

Find Minimum in Rotated Sorted Array

Medium Search in Rotated Sorted Array II

Implementation

Link: http://lintcode.com/en/problem/find-minimum-in-rotated-sorted-array-ii/

class Solution {
public:
    /**
     * @param num: the rotated sorted array
     * @return: the minimum number in the array
     */
    int findMin(vector<int> &num) {
        // write your code here
        if(num.size() == 0) return -1;

        int left = 0;
        int right = num.size() - 1;

        while(left + 1 < right){
            int mid = left + (right - left)/2;

            if(num[mid] == num[left]){
                left++;
            }else if(num[mid] == num[right]){
                right--;
            }else if(num[mid] > num[left]){
                if(num[mid] < num[right]){
                    return num[left];
                }else{
                    left = mid;
                }
            }else{ // num[mid] < num[left]
                right = mid;
            }
        }

        if(num[left] <= num[right]) return num[left];
        if(num[right] < num[left]) return num[right];
        return -1;
    }
};