LeetCode | Find Minimum in Rotated Sorted Array

 

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.

You may assume no duplicate exists in the array.

tag : binary search

//思路与前两天的题一样，即用middle的值与边缘值作比较，从而判断pivot是在middle的左或右
//进而找到有序的一半数组，在这一半数组中找到最小的元素，再移动边缘
public class Solution {
    public int findMin(int[] nums) {
        
        int result = Integer.MAX_VALUE;
        
        int left = 0;
        int right = nums.length - 1;
        
        while(left <= right){
            int middle = (left + right) / 2;
            
            if(nums[middle] < nums[right]){  //说明middle在pivot的右边，m-r段有序
                if(nums[middle] < result){   //num[m]是m-r段最小的元素了
                    result = nums[middle];
                }
                right = middle - 1;
            }else{                           //题目指明无重复，此情况则l-m段有序
                if(nums[left] < result){
                    result = nums[left];
                }
                left = middle + 1;          //关于while循环的终止，当循环到达left=middle时，
            }                               //无论如何下次会left>right从而终止循环
        }
        
        return result;
    }
}