Generate a String 题目链接: http://codeforces.com/contest/710/problem/E Description zscoder wants to generate an input file for some programming competition problem. His input is a string consisting of n letters 'a'. He is too lazy to write a generator s…

[Educational Codeforces Round 16]E. Generate a String 试题描述 zscoder wants to generate an input file for some programming competition problem. His input is a string consisting of n letters 'a'. He is too lazy to write a generator so he will manually ge…

题目链接: http://codeforces.com/problemset/problem/710/E E. Generate a String time limit per test 2 secondsmemory limit per test 512 megabytes 问题描述 zscoder wants to generate an input file for some programming competition problem. His input is a string co…

传送门 题意 Roma在玩一个游戏,一共玩了n局,赢则bourle+1,输则bourle-1,Roma将会在以下情况中退出 1.他赢了k个bourle 2.他输了k个bourle 现在给出一个字符串 'L':lose 'W':win '?':任意 'D':平局 输出一个字符串满足条件(Roma n局后离开要满足上述两个其中之一) 分析 dp题 令dp[i][j]表示进行i-1局比赛后,是否获得j个bourle. 如果第i局为'W': dp[i+1][j+1]=j; 如果第i局为'L':dp[i+…

题意:构造一个由a组成的串,如果插入或删除一个a,花费时间x,如果使当前串长度加倍,花费时间y,问要构造一个长度为n的串,最少花费多长时间. 分析:dp[i]---构造长度为i的串需要花费的最短时间. 1.构造长度为1的串,只能插入,dp[1] = x. 2.当前串的长度i为偶数,可以 (1)长度为i/2的串加倍:dp[i / 2] + y (2)长度为i-1的串插入一个a:dp[i - 1] + x 3.当前串的长度i为奇数,可以 (1)长度为i/2的串加倍,再加上一个a:dp[i / 2]…

Two Arithmetic Progressions 题目链接: http://codeforces.com/contest/710/problem/D Description You are given two arithmetic progressions: a1k + b1 and a2l + b2. Find the number of integers x such that L ≤ x ≤ R and x = a1k' + b1 = a2l' + b2, for some inte…

题目链接:http://codeforces.com/contest/813/problem/B 题意:就是有一个数叫做不幸运数,满足题目的 n = x^a + y^b,现在给你一个区间[l,r],让你找一个在这个区间里面一个最长的区间使得这个区间里面的所有数都不是不幸运数,让你输出最长区间的区间长度 . 先用两个数组将x的n次方和y的n次方存起来,然后暴力枚举,用map将符合的条件的数存起来,不幸运数的区间就是两个幸运数的位置之差相减再减1.(注意map迭代器的用法) #include <bi…

第一次在宿舍打CF 把同宿舍的妹子吵得不行... 特此抱歉QAQ A 题意:给定一个字符串, 最多删掉一个字符,使得剩余字符串字典序最小 n<=2e5 当然"最多"是假的 删了肯定比不删小 所以找到字符串里第一个字符i 满足str[i] > str[i + 1] 然后删掉str[i]显然就是最优的了 要是单调的的话 就把最后一个删了 B 题意:给定一个数n,对n做如下操作 1.如果n = 0 结束操作 2.找到n的最小质因数 3.将n减去它的最小质因数,继续操作1 现在给出…

题目链接:E. Maximum Subsequence 用了一个Meet-in-the-middle的技巧,还是第一次用到这个技巧,其实这个技巧和二分很像,主要是在dfs中,如果数量减小一半可以节约很多的时间.  Meet in the middle(有时候也叫作split and merge)是一种用以获取足够高效解决方案的灵巧的思想.和分治思想非常类似,它将问题分割成两个部分,然后试着合并这两个子问题的结果.好处在于通过使用一点额外的空间,你可以解决两倍规模的原来可以解决的问题. #in…

D. Merge Equals time limit per test2 seconds memory limit per test256 megabytes inputstandard input outputstandard output You are given an array of positive integers. While there are at least two equal elements, we will perform the following operatio…

题目链接:https://codeforces.com/contest/1382/problem/D 题意 给出一个大小为 $2n$ 的排列,判断能否找到两个长为 $n$ 的子序列,使得二者归并排序后能够得到该排列. 题解 将原排列拆分为一个个连续子序列,每次从大于上一子序列首部的元素处分出下一连续子序列,只要将这些子序列按照拆分先后排列,归并排序后一定可以得到原排列. 之后即判断能否将这些子序列排列为两个长为 $n$ 的序列即可,可以用状压 $dp$,也可以用 $01$ 背包. 状态 $dp$…

题目链接:https://codeforces.com/contest/1369/problem/D 题意 最初有一个结点,衍生规则如下: 如果结点 $u$ 没有子结点,添加 $1$ 个子结点 如果结点 $u$ 有 $1$ 个子结点,添加 $2$ 个子结点 如果结点 $u$ 有 $3$ 个子结点,跳过该结点 如: \begin{equation} level = 1, 2, 3,4 \end{equation} 爪形结构如下: 问可以在 $level_n$ 选出几个互不相交的爪形结构. 题解 衍…

题目链接 自己的dp, 不是很好,这道dp题是 完全自己做出来的,完全没看题解,还是有点进步,虽然这个dp题比较简单. 题意:一个k叉树, 每一个对应权值1-k, 问最后相加权值为n, 且最大值至少为d 的路径有多少条. 思路:d[i][l][sum] 表示第i 行最大值为l, 总和为sum的路径数. 注意:我的代码中 sum + j 有可能会超过数组最大值,即越界,刚开始我以为不会产生影响,后来 发现不知道为什么 在数组里越界以后比如 越界到d[][][111] 会对 d[][][1]产生影响…

C. Boredom time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Alex doesn't like boredom. That's why whenever he gets bored, he comes up with games. One long winter evening he came up with a ga…

题意 给定一棵以 \(1\) 号点为根的树.若满足以下条件,则认为节点 \(p\) 处有一个 \(k\) 叉高度为 \(m\) 的堆: 若 \(m = 1\) ,则 \(p\) 本身就是一个 \(k\) 叉高度为 \(1\) 的堆. 若 \(m > 1\) ,则 \(p\) 需要有至少 \(k\) 个儿子满足在儿子处有一个 \(k\) 叉高度为 \(m − 1\) 的堆. 令 \(dp[p][k]\) 表示在 \(p\) 点 \(k\) 叉堆的最大高度,令 \(g[p][k]\) 为 \(p\)…

Greenhouse Effect time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Emuskald is an avid horticulturist and owns the world's longest greenhouse — it is effectively infinite in length. Over th…

Cut Ribbon time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Polycarpus has a ribbon, its length is n. He wants to cut the ribbon in a way that fulfils the following two conditions: After the…

C. Journey time limit per test3 seconds memory limit per test256 megabytes inputstandard input outputstandard output Recently Irina arrived to one of the most famous cities of Berland — the Berlatov city. There are n showplaces to n, and some of them…

[Educational Codeforces Round 16]D. Two Arithmetic Progressions 试题描述 You are given two arithmetic progressions: a1k + b1 and a2l + b2. Find the number of integers x such that L ≤ x ≤ R andx = a1k' + b1 = a2l' + b2, for some integers k', l' ≥ 0. 输入 Th…

[Educational Codeforces Round 16]C. Magic Odd Square 试题描述 Find an n × n matrix with different numbers from 1 to n2, so the sum in each row, column and both main diagonals are odd. 输入 The only line contains odd integer n (1 ≤ n ≤ 49). 输出 Print n lines…

[Educational Codeforces Round 16]B. Optimal Point on a Line 试题描述 You are given n points on a line with their coordinates xi. Find the point x so the sum of distances to the given points is minimal. 输入 The first line contains integer n (1 ≤ n ≤ 3·105)…

[Educational Codeforces Round 16]A. King Moves 试题描述 The only king stands on the standard chess board. You are given his position in format "cd", where c is the column from 'a' to 'h' and dis the row from '1' to '8'. Find the number of moves perm…

这场比赛没有打,后来补了一下,第五题数位dp好不容易才搞出来(我太菜啊). 比赛传送门:http://codeforces.com/contest/1073 A. Diverse Substring 题意:给你个字符串,让你找一个子串满足任意一个字符的个数不超过其他字符的总和,输出yes或no表示否存在,如果存在输出任意一个. 这题只要找两个不同的相邻字符,因为两个字符各一个都不超过其他字符的总和,如果字符串只由一个字符组成或长度等于一才会不存在. 代码如下: #include <iostrea…

A. Digits Sequence Dividing(英文速读) 练习英语速读的题,我还上来昏迷一次....只要长度大于2那么一定可以等于2那么前面大于后面就行其他no 大于2的时候分成前面1个剩下后面一定是对的因为按照数字大小 代码 #include <bits/stdc++.h> using namespace std; int main() { ios::sync_with_stdio(0); cin.tie(0); cout.tie(0); int n; cin>>n;…

感慨 这次比较昏迷最近算法有点飘,都在玩pygame...做出第一题让人hack了,第二题还昏迷想错了 A Minimum Integer(数学) 水题,上来就能做出来但是让人hack成了tle,所以要思考一下具体的过程 原本我是认为直接把d进行累加看什么时候不在那个segment内也就是那个范围之内结果tle 今天思考一下发现有两种情况 ①如果d本来就是小于左边界的那么就输出d就可以了,因为样例明确提示有原来的数也可以 ②然后就是如果d在范围之内或者范围外可以用余数来确定具体的数公式是: an…

Bakery 题目链接: http://codeforces.com/contest/707/problem/B Description Masha wants to open her own bakery and bake muffins in one of the n cities numbered from 1 to n. There are m bidirectional roads, each of whose connects some pair of cities. To bake…

C. The Smallest String Concatenation 题目连接: http://www.codeforces.com/contest/632/problem/C Description You're given a list of n strings a1, a2, ..., an. You'd like to concatenate them together in some order such that the resulting string would be lex…

C. Bear and String Distance 题目连接: http://www.codeforces.com/contest/628/problem/C Description Limak is a little polar bear. He likes nice strings - strings of length n, consisting of lowercase English letters only. The distance between two letters is…

题目链接:http://codeforces.com/problemset/problem/632/C C. The Smallest String Concatenation time limit per test 3 seconds memory limit per test 256 megabytes input standard input output standard output You're given a list of n strings a1, a2, ..., an. Y…

Description he only king stands on the standard chess board. You are given his position in format "cd", where c is the column from 'a' to 'h' and d is the row from '1' to '8'. Find the number of moves permitted for the king. Check the king's mov…