A. Anton and Polyhedrons time limit per test:2 seconds memory limit per test:256 megabytes input:standard input output:standard output Anton's favourite geometric figures are regular polyhedrons. Note that there are five kinds of regular polyhedrons:…

题意:有一个长度为\(n\)的序列,要求在\([1,10^9]\)中找一个\(x\),使得序列中恰好\(k\)个数满足\(\le x\).如果找不到\(x\),输出\(-1\). 题解:先对这个序列排个序,然后首先要注意\(k=0\)的情况 如果\(k=0\)并且序列中含有\(1\),那么我们无论如何都找不到比\(1\)小的数,输出\(-1\),如果不含\(1\),那么只要输出\(a[1]-1\)即可. 如果\(k\ne 0\),那么我们要找前\(k\)个小的数(连续相等的数也算),所以我需要用…

Codeforces Round #404 (Div. 2) 题意:对于 n and m (1 ≤ n, m ≤ 10^18)  找到 1) [n<= m] cout<<n; 2) [n>m]最小的 k => (k -m) * (k-m+1) >= (n-m)*2 成立 思路:二分搜索 #include <bits/stdc++.h> #include <map> using namespace std; #define LL long long…

昨晚玩游戏竟然不小心错过了CF..我是有多浪啊. 今天总算趁着下课时间补了,感觉最后两题还是挺有意思的,写个题解. D: 题目大意: 给出一个括号序列,问有多少个子序列 是k个'(' + k个')' 这样的形式.        n<=200000 解法: 对于每个'('的位置,计算以它为最右边的'('的合法子序列数. 假设它左边(包括它)有$l$个'(', 右边有 $r$个')' ,  如果子序列的长度2k, 那么 方案数有$\binom{l-1}{k-1} * \binom{r}{k}= \b…

题目链接:http://codeforces.com/contest/785 A. Anton and Polyhedrons time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Anton's favourite geometric figures are regular polyhedrons. Note that there…

A. Dasha and Stairs time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output On her way to programming school tiger Dasha faced her first test — a huge staircase! The steps were numbered from one t…

B. Anton and Classes 题目连接: http://codeforces.com/contest/785/problem/B Description Anton likes to play chess. Also he likes to do programming. No wonder that he decided to attend chess classes and programming classes. Anton has n variants when he wil…

A - Anton and Polyhedrons 题目连接: http://codeforces.com/contest/785/problem/A Description Anton's favourite geometric figures are regular polyhedrons. Note that there are five kinds of regular polyhedrons: Tetrahedron. Tetrahedron has 4 triangular face…

A. Mishka and Game time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Mishka is a little polar bear. As known, little bears loves spending their free time playing dice for chocolates. Once in…

B. ZgukistringZ Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/551/problem/B Description Professor GukiZ doesn't accept string as they are. He likes to swap some letters in string to obtain a new one. GukiZ has strings a,…