链接:https://codeforces.com/contest/1282/problem/E 题意:给的是一张平面图,是一个n边形,每次可以切一刀,切出一个三角形,最终切成n-2个三角形.题目给出所切三角形的三个顶点的编号,以及三角形的编号.问你切出的三角形顺序,以及按顺序输出原始n边形顶点的所有编号,可以逆序输出也顺序输出. 题解:有点类似拓扑排序.首先输入三角形三个点,a,b,c,统计出V[a] Xor b Xor c,同理统计V[b],V[c],这样可以保证V[i]的值只能是0 Xor…

You promised your girlfriend a rounded cake with at least SS strawberries. But something goes wrong, you don't have the final cake but an infinite plane with NN strawberries on it. And you need to draw a circle which contains strawberries completely…

题面 CF1282E The Cake Is a Lie \(T\) 组测试数据.每次给一个 \(n\) 边形的三角剖分,求节点顺序和剖分顺序. 数据范围:\(3\le n\le 10^5\),\(\sum n\le 10^5\). 蒟蒻解 这题在炫酷的代码和外表下是一个大水题. 对于每一个剖下来的三角形的边,要么是原多边形的边,要么是割的边. 多边形的边在所有三角形的边中出现 \(1\) 次,割边在所有三角形中出现 \(2\) 次. 所以用 map 记录每条边的出现次数. 然后从一个三角形出发…

C. Vladik and fractions 题目链接 http://codeforces.com/contest/743/problem/C 题面 Vladik and Chloe decided to determine who of them is better at math. Vladik claimed that for any positive integer n he can represent fraction as a sum of three distinct posit…

A. Alyona and mex 题目连接: http://codeforces.com/contest/739/problem/A Description Alyona's mother wants to present an array of n non-negative integers to Alyona. The array should be special. Alyona is a capricious girl so after she gets the array, she…

E. Brackets in Implications Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/550/problem/E Description Implication is a function of two logical arguments, its value is false if and only if the value of the first argument is…

B. Preparing Olympiad Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/550/problem/B Description You have n problems. You have estimated the difficulty of the i-th one as integer ci. Now you want to prepare a problemset for…

B. Equivalent Strings Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/559/problem/B Description Today on a lecture about strings Gerald learned a new definition of string equivalency. Two strings a and b of equal length are…

C. Propagating tree Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/383/problem/C Description Iahub likes trees very much. Recently he discovered an interesting tree named propagating tree. The tree consists of n nodes numb…

C. Love Triangles Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/553/problem/C Description There are many anime that are about "love triangles": Alice loves Bob, and Charlie loves Bob as well, but Alice hates Charlie.…

B. Kyoya and Permutation Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/553/problem/B Description Let's define the permutation of length n as an array p = [p1, p2, ..., pn] consisting of n distinct integers from range from…

C. The Closest Pair Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/312/problem/C Description Currently Tiny is learning Computational Geometry. When trying to solve a problem called "The Closest Pair Of Points In The Plane…

上几次的一道cf题. 题目:http://codeforces.com/contest/376/problem/C 性质: (4)a与b的和除以c的余数(a.b两数除以c在没有余数的情况下除外),等于a,b分别除以c的余数之和(或这个和除以c的余数).例如,23,16除以5的余数分别是3和1,所以(23+16)除以5的余数等于3+1=4.注意:当余数之和大于除数时,所求余数等于余数之和再除以c的余数.例如,23,19除以5的余数分别是3和4,所以(23+19)除以5的余数等于(3+4)除以5的余…

D. Water Tree Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/343/problem/D Description Mad scientist Mike has constructed a rooted tree, which consists of n vertices. Each vertex is a reservoir which can be either empty or…

B. Invariance of Tree Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/576/problem/B Description A tree of size n is an undirected connected graph consisting of n vertices without cycles. Consider some tree with n vertices. W…

题目链接:Codeforces Round #275 (Div. 2) C - Diverse Permutation 题意:一串排列1~n.求一个序列当中相邻两项差的绝对值的个数(指绝对值不同的个数)为k个.求序列. 思路:1~k+1.构造序列前段,之后直接输出剩下的数.前面的构造能够依据,两项差的绝对值为1~k构造. AC代码: #include <stdio.h> #include <string.h> int ans[200010]; bool vis[100010]; i…

题目链接:http://codeforces.com/contest/707/my 看了这位大神的详细分析,一下子明白了.链接:http://blog.csdn.net/queuelovestack/article/details/52269321 搞了两天,终于彻底理解了.本来觉得怎么也不可能和DFS扯上关系,结果以操作的编号建树,对于其他3个操作,直接dfs即可. 在执行操作④之后,书架的状态其实已经回到了之前的某种状态k那么,如果我们从状态k出发,直接去推算出所有经操作④会回到状态k的状态…

题目链接:http://codeforces.com/problemset/problem/793/B 题目大意:告诉你起点和终点,要求你在只能转弯两次的情况下能不能到达终点.能就输出“YES”,不能就输出“NO”. 解题思路:这算是经典的转弯题了,接近半年没写搜索题了,,所以今天先拿这道题开刀吧.这个题关键就是“判重”,如何记录走过的点.我们可以开个三维数组,记录各个坐标各个方向上的转弯数,如果下次在到这个点这个方向,那就比较转弯数,如果这次转弯数大于等于已经记录的转弯数那就不用再找下去了,因…

https://codeforces.com/contest/1062/problem/E 题意 给一颗树n,然后q个询问,询问编号l~r的点,假设可以删除一个点,使得他们的最近公共祖先深度最大.每次询问,输出删除的点和祖先的深度 思路 考虑dfs序来判断v是否在u的子树里: dfn[u]<dfn[v]<=max(dfn[u的子树]) 那么进一步拓展,dfs序之差越大,点就在越分离的地方,这些点的lca一定是lca(max(dfn[u]),min(dfn[u])) 这不仅知道了需要去掉哪个点(…

http://codeforces.com/contest/465/problem/C 给定n和m,以及一个字符串s,s不存在长度大于2的回文子串,现在要求输出一个字典比s大的字符串,且串中字母在一定范围内,并且说同样不存在长度大于2的回文子串. 直接去递归构造即可,从最后一位开始,每次只要判断是否子串中含有回文串,其实仔细想想只要考虑是否存在一个字符和前两个字符中的一个相同即可.不卡时限,裸的判断都能过 #include <cstdio> #include <cstdlib> #…

E. Dasha and Puzzle 题目连接: http://codeforces.com/contest/761/problem/E Description Dasha decided to have a rest after solving the problem. She had been ready to start her favourite activity - origami, but remembered the puzzle that she could not solve…

D. Dreamoon and Sets 题目连接: http://www.codeforces.com/contest/476/problem/D Description Dreamoon likes to play with sets, integers and . is defined as the largest positive integer that divides both a and b. Let S be a set of exactly four distinct inte…

题目链接:http://codeforces.com/problemset/problem/682/C 题目大意:取树上任意一个点v,若点v的子树中有一个点u使得dist(v,u)>a[u]那么称节点v是伤心的.给你一个根为1的树,每个节点有一个权值a[i],每条边也有一个权值w,现在让你删最少的结点,使得树上不存在伤心的点.解题思路:删除最少的点,我们可以反一下,变成找最多的点,使得这些点不伤心.只要对这棵树进行DFS,同时记录路径长度dis,当到达某点u时,若dis>a[u],那么要将u及…

A. Exam Time Limit: 1 Sec  Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/534/problem/A Description An exam for n students will take place in a long and narrow room, so the students will sit in a line in some order. The teacher suspects that…

题目链接: http://codeforces.com/contest/606/problem/D D. Lazy Student time limit per test2 secondsmemory limit per test256 megabytes 问题描述 Student Vladislav came to his programming exam completely unprepared as usual. He got a question about some strange…

E. New Reform 题目连接: http://www.codeforces.com/contest/659/problem/E Description Berland has n cities connected by m bidirectional roads. No road connects a city to itself, and each pair of cities is connected by no more than one road. It is not guara…

B. Sea and Islands Time Limit: 20 Sec  Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/544/problem/B Description A map of some object is a rectangular field consisting of n rows and n columns. Each cell is initially occupied by the sea but yo…

题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=5355 题意:给你n个尺寸大小分别为1,2,3,…,n的蛋糕,要求你分成m份,要求每份中所有蛋糕的大小之和均相同,如果有解,输出“YES”,并给出每份的蛋糕数及其尺寸大小,否则输出“NO” 例如n=5,m=3,即大小尺寸分别为1,2,3,4,5的5个蛋糕,要求分成三份,那么解可以是第一份一个蛋糕,大小为5:第二份两个蛋糕,大小为1.4:第三份两个蛋糕,大小为2.3.这样每份大小之和均为5,满足题目要求…

题目链接:http://codeforces.com/problemset/problem/687/A 题意:给出一个n个点m条边的图,分别将每条边连接的两个点放到两个集合中,输出两个集合中的点,若不可能则输出-1: 思路:通过画图我们不难发现,图中没有出现长度为奇数的环则是可行的,反之则是不行的． 对于这点我们可以直接用dfs搜索+染色,对于当前标记为1的点,我们将其所有儿子标记为2, 对于当前标记为2的点,将其所有儿子标记为1,若出现某个节点的标记与其儿子相同,则有长度为奇数的环. 代码:…

链接:http://codeforces.com/problemset/problem/570/D D. Tree Requests time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Roman planted a tree consisting of n vertices. Each vertex contains a low…