这个题是个想法题 先预处理连通块,然后需要用到一种巧妙暴力,即0变1,1变0,一列列添加删除 复杂度O(n^3) #include <cstdio> #include <iostream> #include <ctime> #include <vector> #include <cmath> #include <map> #include <queue> #include <algorithm> #includ…

Bear and Square Grid 枚举k * k 的位置, 然后接上它周围白色连通块的数量, 再统计完全在k * k范围里的连通块, 这个只要某个连通块全部的方格 在k * k里面就好, 并且k * k是一行一行移的, 所以可以优化到n ^ 3. #include<bits/stdc++.h> #define LL long long #define fi first #define se second #define mk make_pair #define PLL pair<…

E. Bear and Square Grid 题目连接: http://www.codeforces.com/contest/680/problem/E Description You have a grid with n rows and n columns. Each cell is either empty (denoted by '.') or blocked (denoted by 'X'). Two empty cells are directly connected if the…

C. Bear and Square Grid time limit per test 3 seconds memory limit per test 256 megabytes input standard input output standard output You have a grid with n rows and n columns. Each cell is either empty (denoted by '.') or blocked (denoted by 'X'). T…

题目链接:传送门 题目大意:给你一个n*n包含".","X"的图,你有一次机会选择一个k*k的子矩阵,将子矩阵全部变为".",问当操作过后,得到的最大联通子块包含的"."的数目是多少. 题目思路:其实这个题自己只想到了一个暴力的思路,当然TLE没商量,但实际上正确的想法就是先dfs预处理所有"."的联通块,之后的想法技巧性太强了,        操作是模拟将子矩阵右移,直接暴力会TLE,而我们可以想到实际上…

n<=500,n*n的01矩阵,可以选择一个k*k的矩阵全变1,求最大1联通区域. 敢敢n^3..模拟k*k的矩阵的位置,从左到右扫的时候,每变一个位置只会引起边界的信息变化,就记含边界的k*k矩形内的各联通块的大小以及不含边界的k*k的矩形内的0的个数,然后边移动边开个桶更新. #include<stdio.h> #include<string.h> #include<algorithm> #include<stdlib.h> #include<…

题目链接:Codeforces 385C Bear and Prime Numbers 这题告诉我仅仅有询问没有更新通常是不用线段树的.或者说还有比线段树更简单的方法. 用一个sum数组记录前n项和,这个sum数组在打素数表时候就能够求出来,注意一点求素数的内层循环要改成i.不能再写成i + i或者i * i了.原因想想就明确了. 这学期最后一场比赛也结束了,结果不非常惬意但也还好. 总的来说这学收获还是蛮多的. 近期可能就不再做ACM了吧,可能要复习CET6了吧,可能要复习期末考试的内容了吧.…

题目链接:Codeforces 385B Bear and Strings 记录下每一个bear的起始位置和终止位置,然后扫一遍记录下来的结构体数组,过程中用一个变量记录上一个扫过的位置,用来去重. #include <iostream> #include <cstdio> #include <cstring> using namespace std; const int MAX_N = 5000 + 100; char str[MAX_N]; struct Node…

题目链接 Codeforces Round #448 C. Square Subsets 题解 质因数 *质因数 ＝ 平方数,问题转化成求异或方程组解的个数 求出答案就是\(2^{自由元-1}\) ,高消求一下矩阵的秩,完了 或者 由于数很小, 我们只需要对于每个数的质因数装压 对这组数求线性基,n - 线性基中的数就是自由元个数 代码 #include<bits/stdc++.h> using namespace std; inline int read() { int x = 0,f =…

链接 Codeforces 680D Bear and Tower of Cubes 题意 求一个不超过 \(m\) 的最大体积 \(X\), 每次选一个最大的 \(x\) 使得 \(x^3\) 不超过当前剩余体积.问在能选最多个数的情况下,\(X\) 最大是多少 思路 对于每一次选择,首先要保证选完后的剩余体积最大,这样就保证了能选最多个数.然后在这基础上保证 \(X\) 最大. 考虑对于最大的 \(a\),使得 \(a^3<=m\). 如果当前选择的是 \(a\),则剩余体积就是 \(m1…

Codeforces 385C Bear and Prime Numbers 其实不是多值得记录的一道题,通过快速打素数表,再做前缀和的预处理,使查询的复杂度变为O(1). 但是,我在统计数组中元素出现个数时使用了map,以至于后面做前缀和的累加时,每次都要对map进行查询,以至于TLE.而自己一直没有发现,以为是欧拉筛对于这道题还不够优,于是上网搜题解,发现别人的做法几乎一样,但是却能跑过,挣扎了许久才想起是map的原因.map的内部实现是一颗红黑树,每次查询的复杂度为O(logN),在本来时…

[Codeforces 1245D] Shichikuji and Power Grid (最小生成树) 题面 有n个城市,坐标为\((x_i,y_i)\),还有两个系数\(c_i,k_i\).在每个城市建立发电站需要费用\(c_i\).如果不建立发电站,要让城市通电,就需要与有发电站的城市连通.i与j之间连一条无向的边的费用是\((k_i+k_j)\)*两个城市之间的曼哈顿距离.求让每个城市都通电的最小费用,并输出任意一个方案. 分析 把选每个点的代价转成虚拟原点到这个点的边,这个套路很常见,…

[Codeforces 1228E]Another Filling the Grid (排列组合+容斥原理) 题面 一个\(n \times n\)的格子,每个格子里可以填\([1,k]\)内的整数.要保证每行每列的格子上的数最小值为1,有多少种方案 \(n \leq 250,k \leq 10^9\) 分析 这题有\(O(n^3)\)的dp做法,但个人感觉不如\(O(n^2 \log n)\)直接用数学方法求更好理解. 考虑容斥原理,枚举至少有\(i\)行最小值>1,有\(j\)行最小值>1…

[Codeforces 639F] Bear and Chemistry(Tarjan+虚树) 题面 给出一个n个点,m条边的无向图(不保证连通,可能有自环和重边),有q次询问,每次询问给出p个点和q条边,判断加上q条边后,这p个点中的任意一个点对(x,y)是否都满足:能从x走到y,再从y走到x,不经过重复的边.询问强制在线. \((1 ≤ n, q≤ 300 000, 0 ≤ m ≤ 300 000,\sum p \leq 300\ 000,\sum q \leq 300\ 000)\) 分析…

A. Bear and Big Brother time limit per test:1 second memory limit per test:256 megabytes input:standard input output:standard output Bear Limak wants to become the largest of bears, or at least to become larger than his brother Bob. Right now, Limak…

题目链接: http://codeforces.com/problemset/problem/653/C 题意: 给定序列,偶数位的数字比两边都大,则成为nice,只可以交换两个数字,问有多少种交换方式使得最后的序列为nice. 分析: 比赛的时候找规律,找呀找了好久都没看出来....由于只可以交换一次,交换两个数字,所以最多改变的6个数字的关系.那么可以交换成nice的话,原来不满足的肯定很少,直接把这些数字提出来,然后暴力的和序列每个元素交换一下,看看其余不满足的是否变成满足就好啦~~~ 代…

C. Make a Square time limit per test2 seconds memory limit per test256 megabytes inputstandard input outputstandard output You are given a positive integer n, written without leading zeroes (for example, the number 04 is incorrect). In one operation…

算一下复杂度.发现可以直接暴.对于u枚举a和b,判断一下是否连边,更新答案. #include<bits/stdc++.h> using namespace std; int n,m; ; #define PB push_back vector<int> G[maxn]; bool g[maxn][maxn]; int deg[maxn]; const int INF = 0x3f3f3f3f; int main() { //freopen("in.txt",&…

A. Bus to Udayland time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output ZS the Coder and Chris the Baboon are travelling to Udayland! To get there, they have to get on the special IOI bus. The…

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:…

一种巧妙到暴力方式,这题到抽象化:在一个无向图中,找一个度数和最小到三阶到圈. 首先对边进行枚举,这样确定了两个顶点,然后在对点进行枚举,找到一个可以构成三元圈到点,则计算他们到度数和. 最后保存最小到度数和到三元圈即可.   Bear and Three Musketeers Time Limit:2000MS     Memory Limit:262144KB     64bit IO Format:%I64d & %I64u Submit Status Description Do you…

A. Plus and Square Root time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output ZS the Coder is playing a game. There is a number displayed on the screen and there are two buttons, ' + ' (plus) an…

There is No Alternative 题目连接: http://codeforces.com/gym/100803/attachments Description ICPC (Isles of Coral Park City) consist of several beautiful islands. The citizens requested construction of bridges between islands to resolve inconveniences of u…

E. Holes Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/13/problem/E Description Little Petya likes to play a lot. Most of all he likes to play a game «Holes». This is a game for one person with following rules: There are…

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,…

A. Robot Bicorn Attack Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/175/problem/A Description Vasya plays Robot Bicorn Attack. The game consists of three rounds. For each one a non-negative integer amount of points is gi…

A. PawnChess Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/592/problem/A Description Galois is one of the strongest chess players of Byteforces. He has even invented a new variant of chess, which he named «PawnChess». Thi…

题目链接:http://codeforces.com/problemset/problem/385/C 题目大意:给定n个数与m个询问区间,问每个询问区间中的所有素数在这n个数中被能整除的次数之和 解题思路:首先暴力打出一张素数表,最大的素数小于等于n个数中的最大值即可.在打表的过程就统计从2开始到当前素数的总的整除次数(简直简单粗暴),最后对于询问区间,找出该区间内的最小素数与最大素数在素数表中的位置,结果即为s[r]-s[l-1] 代码如下: #include<cmath> #includ…

Recently, the bear started studying data structures and faced the following problem. You are given a sequence of integers x1, x2, ..., xn of length n and m queries, each of them is characterized by two integers li, ri. Let's introduce f(p) to represe…

B. Bear and Friendship Condition time limit per test:1 second memory limit per test:256 megabytes input:standard input output:standard output Bear Limak examines a social network. Its main functionality is that two members can become friends (then th…