Problem Description A while ago it was quite cumbersome to create a message for the Short Message Service (SMS) on a mobile phone. This was because you only have nine keys and the alphabet has more than nine letters, so most characters could only be
即求删掉一个子序列的gcd之和.注意到前后缀gcd的变化次数都是log级的,于是暴力枚举前缀gcd和后缀gcd即可. #include<iostream> #include<cstdio> #include<cmath> #include<cstdlib> #include<cstring> #include<algorithm> using namespace std; #define ll long long #define N
在一个无序序列中找出第k个元素,对于k很小或者很大时可以采取特殊的方法,比如用堆排序来实现 .但是对于与序列长度N成正比的k来说,就不是一件容易的事了,可能最容易想到的就是先将无序序列排序再遍历即可找出第k个元素.由于任何基于比较的排序算法不可能用少于Θ(N lgN)次比较来实现将所有元素排序,所以采用排序的方法的时间复杂度是线性对数级别的. 我们可以借鉴快速排序中将序列划分的思想来实现平均情况下线性级别的算法,算法实现如下: public class KthElement { private
题目大意 https://leetcode.com/problems/kth-smallest-element-in-a-bst/description/ 230. Kth Smallest Element in a BST Given a binary search tree, write a function kthSmallest to find the kth smallest element in it. Note: You may assume k is always valid,