33. Search in Rotated Sorted Array

最新推荐文章于 2020-08-05 08:57:53 发布

转载最新推荐文章于 2020-08-05 08:57:53 发布 · 155 阅读

本文介绍了一种在未知旋转点的升序数组中查找目标值的方法。该数组可能已从某个未知位置旋转，例如从0124567变为4567012。文章提供了一个Java解决方案，通过自定义的二分查找实现高效搜索。

Suppose an array sorted in ascending order 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).

You are given a target value to search. If found in the array return its index, otherwise return -1.

You may assume no duplicate exists in the array.

public class Solution {
    public int search(int[] nums, int target) {
        int start = 0;
        int end = nums.length - 1;
        while (start <= end){
            int mid = (start + end) / 2;
            if (nums[mid] == target)
                return mid;
            if (nums[start] <= nums[mid]){
                 if (target < nums[mid] && target >= nums[start]) 
                    end = mid - 1;
                 else
                    start = mid + 1;
            } 
            if (nums[mid] <= nums[end]){
                if (target > nums[mid] && target <= nums[end])
                    start = mid + 1;
                 else
                    end = mid - 1;
            }
        }
        return -1;
    }
}