题意:有一棵树,对于每个点$i$,给出了它到其他点的距离和$i$,现在要还原这棵树,保证$d_i$两两不同 一个点从$u$移到相邻节点$v$时,若删掉$(u,v)$后$u$这边的连通块大小为$siz_u$,$v$这边的连通块大小为$siz_v$,那么$d_v=d_u-siz_v+siz_u$ 首先,有最大$d_x$的$x$是叶子,并且我们知道它的父亲的$d$为$d_x-(n-1)+1$ 所以考虑按$d$从大到小的顺序确定每个点$x$的父亲:这个点的$d$必须是$d_x-(n-siz_x)+siz…

「ARC103D」 Distance Sums 传送门 水题. 首先如果让你求树上的节点 \(i\) 到其它所有节点的距离和,这是非常简单的,这就是非常常规的换根 \(\texttt{DP}\). 那么,我们可以观察一下这个答案的递推式:\(f_u=f_{fa_u}-siz_u+(n-siz_u)\). 也就是说,如果我们确定了 \(f_u\),那么我们可以确定 \(f_{fa_u}\) 的值. 又根据递推式,我们可以考虑这样的一种构造方式: 首先将 \(f\) 从大到小排序,如果当前 \(f\…

给定$n$个数$d_{i}$,构造一棵$n$个点的树使得$\forall 1\le i\le n,\sum_{j=1}^{n}dist(i,j)=d_{i}$ 其中$dist(i,j)$表示$i$到$j$的路径上所经过的边数,若无解输出-1 $2\le n\le 10^{5}$,$1\le d_{i}\le 10^{12}$,保证$d_{i}$各不相同 1 #include<bits/stdc++.h> 2 using namespace std; 3 #define N 100005 4 #…

ARC103E Tr/ee 首先没有叶子显然不科学,\(s_n\)是1也不怎么科学,\(s_i != s_{n-i}\)同样不怎么科学 特判掉上述情况后先把root记为1,链接(root,i+1)如果\(s_i\)就把root改为i+1 理解一下的话就是对于一个这样的结构 如果\(s_i\)就把它做成一颗紫薯 否则一定要去掉这样的结构 就行了 #include<iostream> #include<cstring> #include<cstdio> #include&l…

Given an integer array nums, return the number of range sums that lie in [lower, upper] inclusive.Range sum S(i, j) is defined as the sum of the elements in nums between indices i and j (i ≤ j), inclusive. Note:A naive algorithm of O(n2) is trivial.…

最近感觉自己思维僵化,啥都不会做了-- ARC103 F Distance Sums 题意 给定第 \(i\) 个点到所有点的距离和 \(D_i\) ,要求构造一棵合法的树.满足第 \(i\) 个点到其他所有点的距离和为 \(D_i\) . \(n \le 10^5\) . 技巧 寻找特殊的量,推出整个树的形态 题解 题解 整棵树里头,最为特殊的点有两类.一个是重心,这是距离和最小的点,另一个是叶子节点,这是距离和最大的节点.考虑如果我们先确定重心,那么接着就不大好往下推了,因为我们并不知道子树…

C - //// 为了防止一些多余的判断,我选择直接记录每个数的个数,然后枚举第一个数,找第一个数之外第二个数改变最少的情况下应该选什么 代码 #include <bits/stdc++.h> #define fi first #define se second #define pii pair<int,int> #define mp make_pair #define pb push_back #define enter putchar('\n') #define space p…

目录 ARC 103 A.//// B.Robot Arms C.Tr/ee D.Distance Sums ARC 103 窝是传送门QwQ A.//// 题意 : 给你\(n\)(\(n\)为偶数)个数 一次操作你可以修改任意一个数 问最少修改几次使得其满足以下条件 \(a_i=a_{i+2}\) \(a_1!=a_2\) 数据约束: \(2 \leq n \leq 10^5\) , \(1 \leq a_i \leq 10^5\) 题解: 对于下标为奇数的记下每个数出现的个数 在满足和偶数…

传送门 C - /\/\/\/ 题意: 给出一个序列\(\{a_i\}\),先要求其满足以下条件: \(a_i=a_{i+2}\) 共有两个不同的数 你现在可以修改任意个数,现问最少修改个数为多少. 思路: 很明显奇偶分类. 记录奇数位置.偶数位置的最大值和最大出现次数的情况: 因为要求两个数不相同,所以还要维护次大. 注意以下细节就是了. Code #include <bits/stdc++.h> using namespace std; typedef long long ll; cons…

Given an integer array nums, return the number of range sums that lie in [lower, upper] inclusive.Range sum S(i, j) is defined as the sum of the elements in nums between indices i and j (i ≤ j), inclusive. Note:A naive algorithm of O(n2) is trivial.…

Given an integer array, return the k-th smallest distance among all the pairs. The distance of a pair (A, B) is defined as the absolute difference between A and B. Example 1: Input: nums = [1,3,1] k = 1 Output: 0 Explanation: Here are all the pairs:…

Given an integer array, return the k-th smallest distance among all the pairs. The distance of a pair (A, B) is defined as the absolute difference between A and B. Example 1: Input: nums = [1,3,1] k = 1 Output: 0 Explanation: Here are all the pairs:…

The Hamming distance between two integers is the number of positions at which the corresponding bits are different. Now your job is to find the total Hamming distance between all pairs of the given numbers. Example: Input: 4, 14, 2 Output: 6 Explanat…

The Hamming distance between two integers is the number of positions at which the corresponding bits are different. Given two integers x and y, calculate the Hamming distance. Note:0 ≤ x, y < 231. Example: Input: x = 1, y = 4 Output: 2 Explanation: 1…

You are given two integer arrays nums1 and nums2 sorted in ascending order and an integer k. Define a pair (u,v) which consists of one element from the first array and one element from the second array. Find the k pairs (u1,v1),(u2,v2) ...(uk,vk) wit…

Given a non-empty string str and an integer k, rearrange the string such that the same characters are at least distance k from each other. All input strings are given in lowercase letters. If it is not possible to rearrange the string, return an empt…

You want to build a house on an empty land which reaches all buildings in the shortest amount of distance. You can only move up, down, left and right. You are given a 2D grid of values 0, 1 or 2, where: Each 0 marks an empty land which you can pass b…

This is a follow up of Shortest Word Distance. The only difference is now word1 could be the same as word2. Given a list of words and two words word1 and word2, return the shortest distance between these two words in the list. word1 and word2 may be…

This is a follow up of Shortest Word Distance. The only difference is now you are given the list of words and your method will be called repeatedly many times with different parameters. How would you optimize it? Design a class which receives a list…

Given a list of words and two words word1 and word2, return the shortest distance between these two words in the list. For example,Assume that words = ["practice", "makes", "perfect", "coding", "makes"]. G…

Given two strings S and T, determine if they are both one edit distance apart. 这道题是之前那道Edit Distance的拓展,然而这道题并没有那道题难,这道题只让我们判断两个字符串的编辑距离是否为1,那么我们只需分下列三种情况来考虑就行了: 1. 两个字符串的长度之差大于1,那么直接返回False 2. 两个字符串的长度之差等于1,那么长的那个字符串去掉一个字符,剩下的应该和短的字符串相同 3. 两个字符串的长度之…

Given two words word1 and word2, find the minimum number of steps required to convert word1 to word2. (each operation is counted as 1 step.) You have the following 3 operations permitted on a word: a) Insert a characterb) Delete a characterc) Replace…

Levenshtein distance,中文名为最小编辑距离,其目的是找出两个字符串之间需要改动多少个字符后变成一致.该算法使用了动态规划的算法策略,该问题具备最优子结构,最小编辑距离包含子最小编辑距离,有下列的公式. 其中d[i-1,j]+1代表字符串s2插入一个字母才与s1相同,d[i,j-1]+1代表字符串s1删除一个字母才与s2相同,然后当xi=yj时,不需要代价,所以和上一步d[i-1,j-1]代价相同,否则+1,接着d[i,j]是以上三者中最小的一项. 算法实现(C#): 假设两个…

1.首先将word文档解压缩为zip /** * 修改后缀名 */ public static String reName(String path){ File file=new File(path); String filename=file.getAbsolutePath(); if(filename.indexOf(".")>=0){ filename=filename.substring(0,filename.lastIndexOf(".")); }…

The Hamming distance between two integers is the number of positions at which the corresponding bits are different. Now your job is to find the total Hamming distance between all pairs of the given numbers. Example: Input: 4, 14, 2 Output: 6 Explanat…

The Hamming distance between two integers is the number of positions at which the corresponding bits are different. Given two integers x and y, calculate the Hamming distance. Note:0 ≤ x, y < 231. Example: Input: x = 1, y = 4 Output: 2 Explanation: 1…

题目: The Hamming distance between two integers is the number of positions at which the corresponding bits are different. Given two integers x and y, calculate the Hamming distance. Note:0 ≤ x, y < 231. Example: Input: x = 1, y = 4 Output: 2 Explanatio…

马氏距离(Mahalanobis distance)是由印度统计学家马哈拉诺比斯(P. C. Mahalanobis)提出的,表示数据的协方差距离.它是一种有效的计算两个未知样本集的相似度的方法.与欧氏距离不同的是它考虑到各种特性之间的联系(例如:一条关于身高的信息会带来一条关于体重的信息,因为两者是有关联的)并且是尺度无关的(scale-invariant),即独立于测量尺度. 对于一个均值为,协方差矩阵为Σ的多变量矢量,其马氏距离为 马氏距离也可以定义为两个服从同一分布并且其协方差矩阵为Σ的…

C. Bear and String Distance time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Limak is a little polar bear. He likes nice strings - strings of length n, consisting of lowercase English letter…

编辑距离 编辑距离(Edit Distance),又称Levenshtein距离,是指两个字串之间,由一个转成另一个所需的最少编辑操作次数.许可的编辑操作包括将一个字符替换成另一个字符,插入一个字符,删除一个字符.一般来说,编辑距离越小,两个串的相似度越大.例如将kitten一字转成sitting:sitten (k→s)sittin (e→i)sitting (→g)俄罗斯科学家Vladimir Levenshtein在1965年提出这个概念. 应用 最小编辑距离通常作为一种相似度计算函数被用…