LeetCode——Find Minimum in Rotated Sorted Array

Description：

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.

随机找一个枢纽，旋转有序数组，找出最小元素。

O(n)解法，线性查找。1ms

public class Solution {
    public int findMin(int[] nums) {
        
        int min = nums[0];
        
        for(int i=1; i<nums.length; i++) {
            if(min > nums[i])
                min = nums[i];
        }
        
        return min;
    }
}

O(logn)解法，二分。0ms

public class Solution {
    public int findMin(int[] nums) {
        
        int n = nums.length - 1;
        
        int left = 0, right = nums.length - 1;
        
        while(left <= right) {
            int mid = left + (right - left) / 2;
            if(nums[mid] > nums[n]) {
                left = mid + 1;
            }
            else {
                right = mid - 1;
            }
        }
        
        return nums[left];
    }
}