[leetcode]Search in Rotated Sorted Array II

这道题目仍然是二分，去掉不可能的部分。用了递归，在重复的情况下，就是有可能最左边的和最右边的相等，此时就不能直接判断出区间外的元素，左右两边同时递归。有重复元素的时候，在bad case的时候会退化为O（n）

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

网上有个思路更简洁，二分。如果相等导致不能二分，则直接跳过这个重复的元素。

class Solution {
public:bool search(int A[], int n, int key) {int l = 0, r = n - 1;while (l <= r) {int m = l + (r - l)/2;if (A[m] == key) return true; //return m in Search in Rotated Array Iif (A[l] < A[m]) { //left half is sortedif (A[l] <= key && key < A[m])r = m - 1;elsel = m + 1;} else if (A[l] > A[m]) { //right half is sortedif (A[m] < key && key <= A[r])l = m + 1;elser = m - 1;} else l++;}return false;}
};

转载于:https://www.cnblogs.com/lautsie/p/3356200.html

[leetcode]Search in Rotated Sorted Array II相关推荐

LeetCode Search in Rotated Sorted Array II
Follow up for "Search in Rotated Sorted Array": What if duplicates are allowed? Would t ...
LeetCode Search in Rotated Sorted Array II -- 有重复的旋转序列搜索
Follow up for "Search in Rotated Sorted Array": What if duplicates are allowed? Would this ...
leetcode - Search in Rotated Sorted Array II
Follow up for "Search in Rotated Sorted Array": What if duplicates are allowed? Would this ...
【leetcode】Search in Rotated Sorted Array II（middle）☆
Follow up for "Search in Rotated Sorted Array": What if duplicates are allowed? Would this ...
leetcode 81 Search in Rotated Sorted Array II ----- java
Follow up for "Search in Rotated Sorted Array": What if duplicates are allowed? Would this ...
LeetCode Online Judge 题目C# 练习 - Search in Rotated Sorted Array II
Follow up for "Search in Rotated Sorted Array": What if duplicates are allowed? Would this ...
[算法题] Search in Rotated Sorted Array ii
题目内容题目来源:LeetCode Suppose an array sorted in ascending order is rotated at some pivot unknown to yo ...
81. Search in Rotated Sorted Array II
题目: Follow up for "Search in Rotated Sorted Array": What if duplicates are allowed? Would ...
Search in Rotated Sorted Array II
Follow up for "Search in Rotated Sorted Array": What if duplicates are allowed? Would this ...

[leetcode]Search in Rotated Sorted Array II

[leetcode]Search in Rotated Sorted Array II相关推荐

最新文章

热门文章