package leetcode;

 /* *

  * 注意问题：

  * 1. 原序列升序、降序问题，两种情况都要考虑

  * 2. 边界问题，如果只有两个元素时要单独考虑，在num[mid]==num[left]判断中考虑

  * 3. 采用2叉查找的思想

  * */

 public class findMinInRotatedSortedArray {

     public int findMin(int[] num)

     {

         int left=0;

         int right=num.length-1;

         if(num[left]>num[right])//原序列是升序排列

         {

             while(left < right)

             {

                 int mid=(left+right)/2;

                 if(num[mid]==num[left])

                     left=mid+1;

                 else if(num[mid]>num[left])

                     left=mid;

                 else

                     right=mid;

             }

         }

         else //原序列是降序排列

         {

             while(left < right)

             {

                 int mid=(left+right)/2;

                 if(num[mid]==num[left])

                     right=mid-1;

                 else if(num[mid]>=num[left])

                     right=mid;

                 else

                     left=mid;

             }

         }

         return num[left];

     }

     public static void main(String[] args)

     {

         int[] arr=new int[3];

         arr[0]=3;

         arr[1]=1;

         arr[2]=2;

         findMinInRotatedSortedArray a=new findMinInRotatedSortedArray();

         System.out.println(a.findMin(arr));

     }

 }