采用二分法,

首先判断中心点是在左边的上升区域,还是在右边的上升区域,以此来更新左右指针。

class Solution {
public:
    int minNumberInRotateArray(vector<int> rotateArray) {
        int left=0, right = rotateArray.size()-1;
        
        while(left < right){
            int mid = left + (right - left) / 2;
            if(rotateArray[left] > rotateArray[right]){
                if(rotateArray[mid] >= rotateArray[left]){
                    left = mid+1;
                }
                else{
                    right = mid;
                }
            }
            else{
                right--;
            }
        }
        return rotateArray[left];
    }
};