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…

Invariance of Tree 题目大意:给你一个有1-n组成的序列p,让你构造一棵树,如果节点a和b之间有一条边,则p[a]和p[b]之间也有一条边. 思路:没啥思路,看了题解菜爆. 我们可以把1-n个数分到若干个集合里边,一个集合里边的元素要满足按顺序转移改变的性质,如果有其中一个集合的元素等于数量等于1 或者其中一个集合的元素数量等于二,并且没有集合有奇数个元素. 因为我们需要用一个集合当作树的基准来构造,将其他集合的元素 连到这个基准上,所以如果这个基准的元素大于三个他们之间必然成…

Div. 2 Multiplication Table (577A) 题意: 给定n行n列的方阵,第i行第j列的数就是i*j,问有多少个格子上的数恰为x. 1<=n<=10^5, 1<=x<=10^9 题解: 送分题…对于每一行,判断是否存在数x即可…也可以枚举x的因子判断是否出现在表内… 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 #include <cstdio> #include <cstring> inline in…

C. Points on Plane Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/576/problem/C Description On a plane are n points (xi, yi) with integer coordinates between 0 and 106. The distance between the two points with numbers a and…

C. Vasya and Petya's Game Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/577/problem/C Description Vasya and Petya are playing a simple game. Vasya thought of number x between 1 and n, and Petya tries to guess the number. P…

B. Modulo Sum Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/577/problem/B Description You are given a sequence of numbers a1, a2, ..., an, and a number m. Check if it is possible to choose a non-empty subsequence aij such…

A. Multiplication Table Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/577/problem/A Description Let's consider a table consisting of n rows and n columns. The cell located at the intersection of i-th row and j-th column co…

http://codeforces.com/contest/576/problem/C 题目大意: 给你一个曼哈顿距离的图,然后要求你找到一个链,链穿了所有的点 然后要求这链的长度<=25*10e8 思路: 分块分成1000块,每个块内y坐标最多走10e6长度,x坐标最多走n*10e3个,n表示一块内的点数 n是一个二次函数维护的东西……所以大概答案最后就是10e3(10e6+10e6) = 2*10e9 因为保证一定有解,所以基本上不会去卡你…

题目大意:在一个平面里有n个点,点坐标的值在1-1e6之间,让你给出一个遍历所有点的顺序,要求每个点走一次,且 曼哈顿距离之和小于25*1e8. 思路:想了一会就有了思路,我们可以把1e6的x,y坐标都分成2000份,每份500,然后这样整个平面就被分成 了2000*2000个区域,然后按区域输出点就行了. #include<bits/stdc++.h> using namespace std; int n; vector<][]; int main() { scanf("%d…

E A tree of size n is an undirected connected graph consisting of n vertices without cycles. Consider some tree with n vertices. We call a tree invariant relative to permutation p = p1p2... pn, if for any two vertices of the tree u andv the condition…