题意:给了一棵树以及每个节点的颜色,1代表黑,0代表白,求将这棵树拆成k棵树,使得每棵树恰好有一个黑色节点的方法数 解法:树形DP问题.定义: dp[u][0]表示以u为根的子树对父亲的贡献为0 dp[u][1]表示以u为根的子树对父亲的贡献为1 现在假设u为白色,它的子树有x,y,z,那么有 dp[u][1]+=dp[x][1]*dp[y][0]*dp[z][0]+dp[x][0]*dp[y][1]*dp[z][0]+dp[x][0]*dp[y][0]*dp[z][1] dp[u][0]+=d…

题目链接 D. Appleman and Tree time limit per test :2 seconds memory limit per test: 256 megabytes input :standard input output:standard output Appleman has a tree with n vertices. Some of the vertices (at least one) are colored black and other vertices a…

题目传送门 /* 贪心:每次把一个丢掉,选择最小的.累加求和,重复n-1次 */ /************************************************ Author :Running_Time Created Time :2015-8-1 13:20:01 File Name :A.cpp *************************************************/ #include <cstdio> #include <algori…

C. Appleman and a Sheet of Paper   Appleman has a very big sheet of paper. This sheet has a form of rectangle with dimensions 1 × n. Your task is help Appleman with folding of such a sheet. Actually, you need to perform q queries. Each query will hav…

A. Appleman and Easy Task time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Toastman came up with a very easy task. He gives it to Appleman, but Appleman doesn't know how to solve it. Can you…

题目链接: http://codeforces.com/problemset/problem/337/D D. Book of Evil time limit per test2 secondsmemory limit per test256 megabytes 问题描述 Paladin Manao caught the trail of the ancient Book of Evil in a swampy area. This area contains n settlements num…

A - Ostap and Grasshopper zz题能不能跳到  每次只能跳K步 不能跳到# 问能不能T-G  随便跳跳就可以了  第一次居然跳越界0.0  傻子哦  WA1 n,k = map(int,input().split()) s = input() i = 0 st = -1 def jump(st): while(st<n): st+=k if(st>=n or s[st]=='#'): return "NO" if(s[st]=='T' or s[st…

C. Karen and Supermarket     On the way home, Karen decided to stop by the supermarket to buy some groceries. She needs to buy a lot of goods, but since she is a student her budget is still quite limited. In fact, she can only spend up to b dollars.…

Codeforces Round #267 (Div. 2) C. George and Job题目链接请点击~ The new ITone 6 has been released recently and George got really keen to buy it. Unfortunately, he didn't have enough money, so George was going to work as a programmer. Now he faced the follow…

吐槽:一辈子要在DIV 2混了. A,B,C都是简单题,看AC人数就知道了. A:如果我们定义数组为N*N的话就不用考虑边界了 #include<iostream> #include <string> #include <vector> #include<cstring> #include<cstdio> #include<cmath> #include<string> #include<algorithm>…