LeetCode 33. Search in Rotated Sorted Array（旋转数组搜索）

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本文介绍了一种解决LeetCode上搜索旋转排序数组问题的方法。该问题要求在一个未知旋转点的有序数组中查找目标值并返回其索引。文章提供了一个详细的Java实现方案，通过判断数组的旋转情况来进行二分查找。

原题网址：https://leetcode.com/problems/search-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).

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.

方法：分情况进行查找。

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