F. The Sum of the k-th Powers 题目连接: http://www.codeforces.com/contest/622/problem/F Description There are well-known formulas: , , . Also mathematicians found similar formulas for higher degrees. Find the value of the sum modulo 109 + 7 (so you shoul…
The Sum of the k-th Powers There are well-known formulas: , , . Also mathematicians found similar formulas for higher degrees. Find the value of the sum modulo 109 + 7 (so you should find the remainder after dividing the answer by the value 109 + 7).…
Educational Codeforces Round 40 F. Runner's Problem 题意: 给一个$ 3 * m \(的矩阵,问从\)(2,1)$ 出发 走到 \((2,m)\) 的方案数 \(mod 1e9 + 7\), 走的规则和限制如下: From the cell (i, j) you may advance to: (i - 1, j + 1) - only if i > 1, (i, j + 1), or (i + 1, j + 1) - only if i <…
A. Tricky Sum Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/598/problem/A Description In this problem you are to calculate the sum of all integers from 1 to n, but you should take all powers of two with minus in the sum.…
F. MEX Queries time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output You are given a set of integer numbers, initially it is empty. You should perform n queries. There are three different types…
F. Four Divisors 题目连接: http://www.codeforces.com/contest/665/problem/F Description If an integer a is divisible by another integer b, then b is called the divisor of a. For example: 12 has positive 6 divisors. They are 1, 2, 3, 4, 6 and 12. Let's def…
F. Magic Matrix 题目连接: http://www.codeforces.com/contest/632/problem/F Description You're given a matrix A of size n × n. Let's call the matrix with nonnegative elements magic if it is symmetric (so aij = aji), aii = 0 and aij ≤ max(aik, ajk) for all…
F. Xors on Segments 题目连接: http://www.codeforces.com/contest/620/problem/F Description You are given an array with n integers ai and m queries. Each query is described by two integers (lj, rj). Let's define the function . The function is defined for o…
F. Bear and Fair Set 题目连接: http://www.codeforces.com/contest/628/problem/F Description Limak is a grizzly bear. He is big and dreadful. You were chilling in the forest when you suddenly met him. It's very unfortunate for you. He will eat all your coo…
F. Frogs and mosquitoes time limit per test 2 seconds memory limit per test 512 megabytes input standard input output standard output There are n frogs sitting on the coordinate axis Ox. For each frog two values xi, ti are known — the position and th…
F. Guards In The Storehouse time limit per test 1.5 seconds memory limit per test 512 megabytes input standard input output standard output Polycarp owns a shop in the capital of Berland. Recently the criminal activity in the capital increased, so Po…
Codeforces Educational Codeforces Round 44 (Rated for Div. 2) F. Isomorphic Strings 题目连接: http://codeforces.com/contest/985/problem/F Description You are given a string s of length n consisting of lowercase English letters. For two given strings s an…
[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 26 困到不行的场,等着中午显示器到了就可以美滋滋了 A. Text Volume time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output You are given a text of single-space separated words, consisting of sm…
Educational Codeforces Round 65 (Rated for Div. 2)题解 题目链接 A. Telephone Number 水题,代码如下: Code #include <bits/stdc++.h> using namespace std; typedef long long ll; const int N = 2e5 + 5; int a[N] ; int n, T; char s[N] ; int main() { cin >> T; whil…
