Find Minimum in Rotated Sorted Array

 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));
     }
 }