One, the problem
1. Move the first elements of an array to the end of the array, which we call the rotation of the array. Input a rotation of an ascending array, and output the smallest element of the rotated array. For example, the array [3,4,5,1,2] is a rotation of [1,2,3,4,5], and the minimum value of the array is 1.
2. Examples
Input: [3,4,5,1,2]
Output: 1
Input: [2,2,2,0,1]
Output: 0
Two, the solution
1. Violence Law
Start traversing from the element with subscript 0
For each comparison, if the current element is larger than the next adjacent element, the corresponding next element is the minimum value
If there is no 2 in the last element in the query, the subscript element is the smallest element.
2. Dichotomy
Store elements in order (required)
package com.haoxiansheng.demo01.SwordfingerOffer;
import lombok.extern.slf4j.Slf4j;
import java.util.Vector;
/**
* @author flame
* @data 2020/10/24
*/
@Slf4j
public class MinArrayDemo {
public static void main(String[] args) {
int [] arr = {
2, 3, 4, 5, 0, 1};
log.info("minArray=>{}", minArray(arr));
}
// 暴力匹配 + 二分查找
// 时间复杂度为 O(n)
// 空间复杂度：O(1)
public static int minArray(int [] numbers) {
int left = 0;
int right = numbers.length -1;
if (right == 0) {
return numbers[0];
}
while (left < right) {
int mid = left + (right - left) / 2;
if (numbers[mid] > numbers[right]) {
left = mid + 1;
} else if(numbers[mid] < numbers[right]) {
right = mid;
} else if (numbers[mid] == numbers[right]) {
right --; // 暴力缩减范围
}
}
return numbers[left];
}
}