Friends and Subsequences 题目链接: http://acm.hust.edu.cn/vjudge/contest/121333#problem/H Description Mike and !Mike are old childhood rivals, they are opposite in everything they do, except programming. Today they have a problem they cannot solve on the…

枚举,二分,$RMQ$. 对于一个序列来说,如果固定区间左端点,随着右端点的增大,最大值肯定是非递减的,最小值肯定是非递增的. 因此,根据这种单调性,我们可以枚举区间左端点$L$,二分找到第一个位置${{p_1}}$,使得$\mathop {\max }\limits_{i = L}^{{p_1}} {a_i} = \mathop {\min }\limits_{i = L}^{{p_1}} {b_i}$:再次二分找到最后一个位置${{p_2}}$,使得$\mathop {\max }\limi…

689D - Friends and Subsequences 题意: 大致跟之前题目一样,用ST表维护a[]区间max,b[]区间min,找出多少对(l,r)使得maxa(l,r) == minb(l,r) 切题的感觉很爽唉 同样而二分查找,找最小和最大下标满足条件 cf中%I64d, 一般是%lld 代码: #include<bits/stdc++.h> #define ll long long const int maxn=200010; int sta[maxn][18]; int s…

题目链接: D. Friends and Subsequences time limit per test 2 seconds memory limit per test 512 megabytes input standard input output standard output Mike and !Mike are old childhood rivals, they are opposite in everything they do, except programming. Toda…

time limit per test2 seconds memory limit per test512 megabytes inputstandard input outputstandard output Mike and !Mike are old childhood rivals, they are opposite in everything they do, except programming. Today they have a problem they cannot solv…

Sereja has a sequence that consists of n positive integers, a1, a2, ..., an. First Sereja took a piece of squared paper and wrote all distinct non-empty non-decreasing subsequences of sequence a. Then for each sequence written on the squared paper, S…

Let's call a non-empty sequence of positive integers a1, a2... ak coprime if the greatest common divisor of all elements of this sequence is equal to 1. Given an array a consisting of n positive integers, find the number of its coprime subsequences.…

[题目链接]:http://codeforces.com/contest/803/problem/F [题意] 给你一个序列; 问你这个序列里面有多少个子列; 且这个子列里面的所有数字互质; [题解] 计算cnt[x]; 表示数组里有多少个数是x的倍数; 则某个子列里面所有的数字都能被x整除的子列个数为2cnt[x]−1 把这个值记为f[x]; 则我们用需要用容斥原理; 把所有能被2,3,..n整除的子列删除掉; 这里面会有重复计数的问题; 解决方式是,从大到小枚举f[x] 然后对于y=i*x的…

题目大意:给出两个数组,求第一个数组区间内的最大值和第二个区间内的最小值相同的区间有多少种. 题目思路:通过预处理(O(n*Logn))后,每次查询的时间复杂度为O(1),但是如果暴力查询O(n*n)依然会超时,因为最大值,最小值单调性的原因,通过二分来优化查询过程. 首先是预处理,用动态规划(DP)解决.设A[i]是要求区间最值的数列,F[i, j]表示从第i个数起连续2^j个数中的最大值.例如数列3 2 4 5 6 8 1 2 9 7,F[1,0]表示第1个数起,长度为2^0=1的最大值,其…

Description 题库链接 定义 \(F(x)\) 为 \(F(x-1)\) 与 \(F(x-2)\) 的连接(其中 \(F(0) = "0",F(1) = "1"\) ).给出一个长度为 \(n\) 的 \(01\) 字符串 \(s\) ,询问 \(s\) 在 \(F(x)\) 的所有子序列中出现了多少次. \(1\leq n\leq 100,0\leq x\leq 100\) Solution 首先 \(F(x)\) 是递归来定义的,显然我们可以递推来计算…