LeetCode 32 Search in Rotated Sorted Array

最新推荐文章于 2024-05-03 20:14:24 发布

mlweixiao

最新推荐文章于 2024-05-03 20:14:24 发布

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本文介绍了一种用于在已排序并旋转的数组中搜索目标值的算法，该算法利用折半查找策略，实现时间复杂度为O(log n)。通过比较中间元素与数组边界元素，动态调整搜索区间，最终定位到目标值或返回-1。

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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.

思路：折半查找

public class Solution {
	public int search(int[] A, int target) {
		if(A==null||A.length==0) return -1;
		
		int left=0;
		int right=A.length-1;
		int mid;
		while(left<=right){
			mid=(left+right)/2;
			if(target==A[mid]) return mid;
			
			if(A[mid]<A[right]){
				if(target<=A[right]&&target>A[mid]) left=mid+1;
				else right=mid-1;
			}else{
				if(A[left]<=target&&target<A[mid]) right=mid-1;
				else left=mid+1;
			}
		}
		
		return -1;
	}
}