来自FallDream的博客,未经允许,请勿转载, 谢谢. 给你两棵树,一棵比较大(n<=1000),一棵比较小(m<=12) 问第一棵树中有多少个连通子树和第二棵同构. 答案取膜1e9+7 考虑在大树中随便选个根,然后在小的那棵那里枚举一个根作为大树中深度最小的节点(注意哈希判同构) 然后f[x][y]表示大树的x节点作为小树的y节点的方案数. 如果y是叶子结点,f[x][y]=1 否则要用x的儿子中的一些节点表示y的所有叶子节点. 考虑一个状压dp,g[i][s]表示前i个儿子表示了小树的…

Educational Codeforces Round 17 A. k-th divisor 水题,把所有因子找出来排序然后找第\(k\)大 view code //#pragma GCC optimize("O3") //#pragma comment(linker, "/STACK:1024000000,1024000000") #include<bits/stdc++.h> using namespace std; function<voi…

Educational Codeforces Round 35 (Rated for Div. 2) https://codeforces.com/contest/911 A 模拟 #include<bits/stdc++.h> using namespace std; #define lson l,mid,rt<<1 #define rson mid+1,r,rt<<1|1 #define IT set<ll>::iterator #define sqr(…

Educational Codeforces Round 67 CF1187B Letters Shop 二分 https://codeforces.com/contest/1187/submission/56313177 CF1187C Vasya And Array 直接构造 https://codeforces.com/contest/1187/submission/56316127 CF1187D Subarray Sorting 这题等System Test后更吧... CF1187E…

Educational Codeforces Round 41 (Rated for Div. 2) E. Tufurama (CDQ分治 求 二维点数) time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output One day Polycarp decided to rewatch his absolute favourite epi…

[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…

[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…