随笔分类 - CodeForces
摘要：Mr. Kitayuta has just bought an undirected graph with n vertices and m edges. The vertices of the graph are numbered from 1 to n. Each edge, namely ed
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摘要：n players are going to play a rock-paper-scissors tournament. As you probably know, in a one-on-one match of rock-paper-scissors, two players choose t
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摘要：Piegirl found the red button. You have one last chance to change the inevitable end. The circuit under the button consists of n nodes, numbered from 0
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摘要：Permutation p is an ordered set of integers p1, p2, ..., pn, consisting of n distinct positive integers, each of them doesn't exceed n. We'll denote t
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摘要：In an attempt to make peace with the Mischievious Mess Makers, Bessie and Farmer John are planning to plant some flower gardens to complement the lush
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摘要：As Gerald, Alexander, Sergey and Gennady are already busy with the usual New Year chores, Edward hastily decorates the New Year Tree. And any decent N
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摘要：Sereja is interested in intervals of numbers, so he has prepared a problem about intervals for you. An interval of numbers is a pair of integers [l, r
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摘要：D1. Great Vova Wall (Version 1)： 题意：给定长度为N的墙，以及每个位置的一些高度，现在让你用1*2的砖和2*1的砖去铺，问最后能否铺到高度一样。 思路：分析其奇偶性，在一个位置加1*2的砖，其奇偶性不变。在相邻的而且高度相同的位置加2*1的砖，两个奇偶行都改变。那么我
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摘要：题意：N,K,L，以及给定长度为N的序列，表示其对应的颜色，-1表示还没有涂色，现在让你去涂色，使得最后没有大于等于L的连续的同色的情况。 思路：我们用dp[i][j]表示第i个位置颜色为j的合法方案数，用sum[i]表示dp[i][1]+dp[i][2]+...dp[i][k]。 那么a[i]==
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摘要：A. Definite Game： 题意：输入N，输出最小的结果N-x，其中x不少N的因子。 思路：N=2时，输出2；其他情况输出1；因为N>2时，N-1不会是N的因子。 #include<bits/stdc++.h> #define rep(i,a,b) for(int i=a;i<=b;i++)
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摘要：题意：给定无向图，让你给点加权（1，2，3）,使得每条边是两端点点权和维奇数。 思路：一个连通块是个二分图，判定二分图可以dfs，并查集，2-sat染色。 这里用的并查集（还可以带权并查集优化一下，或者干脆用dfs）。 计数的时候每个连通块单独考虑，我们从连通块的第一个点开始dfs，如果是该填奇数点
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摘要：题意：给定N个K维的点，Q次操作，或者修改点的坐标；或者问[L,R]这些点中最远的点。 思路：因为最后一定可以表示维+/-(x1-x2)+/-(y1-y2)+/-(z1-z2)..... 所以我们可以保存到线段树里，每次求区间最大值和最小值即可。 注意到我们可以先确定一个点的正负号，所以时间和空间节
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摘要：题意：给定长度为N的a数组，和b数组，a和b都是1到N的排列； 有两种操作，一种是询问[L1,R1]，[L2,R2]；即问a数组的[L1,R1]区间和b数组的[L2,R2]区间出现了多少个相同的数字。 一种是修改b数组两个位置的值。 思路：如果把b数组每个数取对应a数组对应数的位置，即按照b的下标建
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摘要：A. The Fair Nut and the Best Path 题意：给定有点权，有边权的树，让你选择一条链（也可以是只有一个点），使得点权之和-边权最大。 思路：裸的树形DP，我们用dp[i]表示i的子树里某个点到i这条链的最大值，然后用次大值更新答案即可。 具体的，每个dp[i]初始化=a[
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摘要：You are given two integers l l and r r (l≤r l≤r ). Your task is to calculate the sum of numbers from l l to r r (including l l and r r ) such that eac
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摘要：You are a given a list of integers a 1 ,a 2 ,…,a n a1,a2,…,an and s s of its segments [l j ;r j ] [lj;rj] (where 1≤l j ≤r j ≤n 1≤lj≤rj≤n ). You need t
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摘要：Vasya has a tree consisting of n n vertices with root in vertex 1 1 . At first all vertices has 0 0 written on it. Let d(i,j) d(i,j) be the distance b
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摘要：Graph constructive problems are back! This time the graph you are asked to build should match the following properties. The graph is connected if and
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摘要：Petya has a simple graph (that is, a graph without loops or multiple edges) consisting of n n vertices and m m edges. The weight of the i i -th vertex
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摘要：You are given array a a of length n n . You can choose one segment [l,r] [l,r] (1≤l≤r≤n 1≤l≤r≤n ) and integer value k k (positive, negative or even ze
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