D. Tanya and Password Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/508/problem/D Description While dad was at work, a little girl Tanya decided to play with dad's password to his secret database. Dad's password is a stri…

传送门 题目 \[ \begin{aligned} &f_n=c^{2*n-6}f_{n-1}f_{n-2}f_{n-3}&\\ \end{aligned} \] 思路 我们通过迭代发现\(f_n\)其实就是由\(c^{t_1},f_1^{t_2},f_2^{t_3},f_3^{t_4}\)相乘得到,因此我们可以分别用矩阵快速幂求出\(t_1,t_2,t_3,t_4\),最后用快速幂求得答案. 对于\(n<=3\)的我们直接输出即可,\(n>3\)的我们先将\(n\)减去\(3…

D. Recover it! Authors guessed an array aa consisting of nn integers; each integer is not less than 22 and not greater than 2⋅1052⋅105. You don't know the array aa, but you know the array bb which is formed from it with the following sequence of oper…

题目链接 给你n个长度为3的子串, 这些子串是由一个长度为n+2的串分割得来的, 求原串, 如果给出的不合法, 输出-1. 一个欧拉通路的题, 将子串的前两个字符和后两个字符看成一个点, 比如acb, 就是ac->cb. 然后建图. #include <iostream> #include <vector> #include <cstdio> #include <cstring> #include <algorithm> #include…

题目传送门 /* 贪心 + 模拟:首先,如果蜡烛的燃烧时间小于最少需要点燃的蜡烛数一定是-1(蜡烛是1秒点一支), num[g[i]]记录每个鬼访问时已点燃的蜡烛数,若不够,tmp为还需要的蜡烛数, 然后接下来的t秒需要的蜡烛都燃烧着,超过t秒,每减少一秒灭一支蜡烛,好!!! 详细解释:http://blog.csdn.net/kalilili/article/details/43412385 */ #include <cstdio> #include <algorithm> #i…

题目传送门 /* 题意:从前面找一个数字和末尾数字调换使得变成偶数且为最大 贪心:考虑两种情况:1. 有偶数且比末尾数字大(flag标记):2. 有偶数但都比末尾数字小(x位置标记) 仿照别人写的,再看自己的代码发现有清晰的思维是多重要 */ #include <cstdio> #include <iostream> #include <algorithm> #include <cmath> #include <cstring> #include…

A. Pasha and Pixels     题意就是给一个n*m的矩阵,k次操作,一开始矩阵全白,一次操作可以染黑一个格子,问第几次操作可以使得矩阵中存在一个2*2的黑色矩阵.直接模拟即可 代码: #include<cstdio> #include<algorithm> #include<map> #include<cstring> #include<vector> #include<cmath> #include<stri…

http://codeforces.com/contest/508/problem/D 以上是题目链接 题目大意 给n个字符串看能不能链接在一起 因为 三个三个分割 所以字符串 如abc ab作为起点 bc作为终点 hash思想 加细节处理 欧拉图均满足 #include<cstdio> #include<map> //#include<bits/stdc++.h> #include<vector> #include<stack> #includ…

C. Tanya and Toys 题目链接http://codeforces.com/contest/659/problem/C Description In Berland recently a new collection of toys went on sale. This collection consists of 109 types of toys, numbered with integers from 1 to 109. A toy from the new collectio…

C. Tanya and Toys 题目连接: http://www.codeforces.com/contest/659/problem/C Description In Berland recently a new collection of toys went on sale. This collection consists of 109 types of toys, numbered with integers from 1 to 109. A toy from the new col…