[LeetCode]540. Single Element in a Sorted Array
来源:互联网 发布:学党史,知国情,圆梦想 编辑:程序博客网 时间:2024/05/12 21:07
[LeetCode]540. Single Element in a Sorted Array
题目描述
思路
开始的想法,直接用位操作,异或即可得到结果,但是需要o(n)时间
题目要求是o(logn),并且给出数组是有序的,因此可以使用二分的方法来做
对于整个数组,取mid,如果mid为偶数,判断mid值是否和mid+1相等,如果相等,则说明只出现一次的数在右边,需要向右边找,原因,mid为偶数时,分割成的两段数组长度均为偶数,如果mid和mid+1相等,那么除去这个mid+1的值,只剩奇数个数,要找的数必然在这奇数个数中,同理可以推断mid为奇数时候的情况
代码
#include <iostream>#include <vector>using namespace std;class Solution {public: int singleNonDuplicate(vector<int> & nums) { /* int res = 0; for (int num : nums) res ^= num; return res; */ int start = 0, end = nums.size() - 1; while (start < end) { int mid = (start + end) / 2; if (mid % 2 == 0) { if (mid + 1 < nums.size() && nums[mid] == nums[mid + 1]) start = mid + 2; else if (mid - 1 >= 0 && nums[mid - 1] == nums[mid]) end = mid - 2; else return nums[mid]; } else { if (mid + 1 < nums.size() && nums[mid] == nums[mid + 1]) end = mid - 1; else if (mid - 1 >= 0 && nums[mid - 1] == nums[mid]) start = mid + 1; } } return nums[start]; }};int main() { Solution s; vector<int> nums = { -1, -1, 3, 3, 5, 7, 7, 9, 9 }; cout << s.singleNonDuplicate(nums) << endl; system("pause"); return 0;}
阅读全文
1 0
- LeetCode (Single Element in a Sorted Array)
- LeetCode | 540. Single Element in a Sorted Array
- {LeetCode} 540. Single Element in a Sorted Array
- LeetCode 540. Single Element in a Sorted Array
- LeetCode 540. Single Element in a Sorted Array
- [LeetCode]540. Single Element in a Sorted Array
- leetcode 540. Single Element in a Sorted Array
- [LeetCode]540. Single Element in a Sorted Array
- leetcode 540. Single Element in a Sorted Array
- leetcode 540. Single Element in a Sorted Array 题解
- leetcode 540. Single Element in a Sorted Array
- leetcode 540. Single Element in a Sorted Array
- 【LeetCode】540. Single Element in a Sorted Array
- [LeetCode] 540. Single Element in a Sorted Array
- LeetCode 540. Single Element in a Sorted Array
- leetcode 540. Single Element in a Sorted Array
- [Leetcode] 540. Single Element in a Sorted Array 解题报告
- 540. Single Element in a Sorted Array
- hive编程指南之数据类型
- C
- Angular 的响应式表单
- 使用git
- Windows linux子系统(二)----常见功能使用
- [LeetCode]540. Single Element in a Sorted Array
- L2-005. 集合相似度
- 代码流程控制结构和日常生活
- Java实现身份证获取年龄
- HDU6058-思维好题-维护第k大-多校3-Kanade's sum
- 快速排序
- C语言之结构体
- js重复某个字符串n次 | 字符串转数组
- 利用Excel和bat批处理命令 批量创建文件夹