Educational Codeforces Round 39 (Rated for Div. 2) G 题意: 给一个序列\(a_i(1 <= a_i <= 10^{9}),2 <= n <= 200000\), 如果至多删除其中的一个数之后该序列为严格上升序列,那么称原序列为几乎严格上升序列. 现在每次将序列中的任意数字变成任意数字,问最少要操作几次才能将序列变成几乎严格上升子序列. 思路: 如果不考虑删除,求让整个序列都变成严格上升子序列的次数 求出\(序列a_i - i\)…

Educational Codeforces Round 39  D. Timetable 令\(dp[i][j]\)表示前\(i\)天逃课了\(j\)节课的情况下,在学校的最少时间 转移就是枚举第\(i\)天逃了\(x\)节课,然后取当天逃\(x\)节课情况下在学校的最小值即可 view code #pragma GCC optimize("O3") #pragma GCC optimize("Ofast,no-stack-protector") #include…

2018-03-11 http://codeforces.com/contest/946/problem/D D. Timetable time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Ivan is a student at Berland State University (BSU). There are n days in…

题: OvO http://codeforces.com/contest/946/problem/E CF 946E 解: 记读入串为 s ,答案串为 ans,记读入串长度为 len,下标从 1 开始. 分三种情况讨论 1.数字位数为奇数,设数字位数为 len,则输出 ( len-1 ) 个 9 即可 ,最低位为 或者,其他位为 ,(即 100001,100 这些形式),记数字位数为 len,则输出 ( len-2 ) 个 9 即可 3.数字位数为偶数,而并非是第二种情况,那么进行一次 dfs…

https://zh.wikipedia.org/wiki/%E8%BC%BE%E8%BD%89%E7%9B%B8%E9%99%A4%E6%B3%95 取模也是一样的,就当多减几次. 在欧几里得最初的描述中,商和余数是通过连续的减法来计算的,即从rk−2中不断减去rk−1直到小于rk−1.一个更高效的做法是使用整数除法和模除来计算商和余数: rk ≡ rk−2 mod rk−1 在欧几里得定义的减法版本,取余运算被减法替换 while (b!=0) { if (a>b) a=a-b; else…

D. Timetable time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Ivan is a student at Berland State University (BSU). There are n days in Berland week, and each of these days Ivan might have s…

You have two variables a and b. Consider the following sequence of actions performed with these variables: If a = 0 or b = 0, end the process. Otherwise, go to step 2; If a ≥ 2·b, then set the value of a to a - 2·b, and repeat step 1. Otherwise, go t…

[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…