//[4,5,6,7,0,1,2] find the minimum number
//
// Rotated sorted array
//        /
//  A    /
//------------------------------------- 
//            /       B
//           /
// Use B as point 
// First position <= last number
//(Wrong: First position <= or < First Number
// if the array is increasing order, cannot use A
class Solution {
public:
    /**
     * @param nums: a rotated sorted array
     * @return: the minimum number in the array
     */
    int findMin(vector<int> &nums) {
        // write your code here
        int size = nums.size();
        if (size == 0) {
            return -1;
        }

        int start = 0;
        int end = size - 1;

        while (start + 1 < end) {
            int mid = (end - start) / 2 + start;
            if (nums[mid] >= nums[end]) {
                start = mid;
            } else {
                end = mid;
            }
        }
        if (nums[start] < nums[end]) {
            return nums[start];
        } else {
            return nums[end];
        }
    }
};