http://acm.hdu.edu.cn/showproblem.php?pid=6128 题意:有一个a数列,并且每个数都小于p,现在要求有多少对$(i,j)$满足$\frac{1}{a_i+a_j} \equiv \frac{1}{a_i}+\frac{1}{a_j} \mod p$,0没有逆元. 思路:根据同余的性质对式子进行化简,在一个同余式两边同时做加法.减法或乘法仍保持同余. 先可以化简为 $1 \equiv 1+\frac{a_j}{a_i}+1+\frac{a_i}{a_j}…

题目链接 Problem Description There are n nonnegative integers a1-n which are less than p. HazelFan wants to know how many pairs i,j(1≤i<j≤n) are there, satisfying 1ai+aj≡1ai+1aj when we calculate module p, which means the inverse element of their sum equ…

题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=6128 题意:给你n个数,问你有多少对i,j,满足i<j,并且1/(ai+aj)=1/ai+1/aj 在%p意义下. 解法:官方题解说是用二次剩余来解,但是我并不会这玩意了.在网上看到一位大佬没有二次剩余直接通过推公式做出了这题,真是神奇.http://www.cnblogs.com/bin-gege/p/7367337.html  将式子通分化简后可得(ai2+aj2+ai*aj)%p=0 .然后两…

Description 给nn个小于pp的非负整数a1,-,na1,-,n,问有多少对(i,j)(1≤i<j≤n)(i,j)(1≤i<j≤n)模pp在意义下满足1ai+aj≡1ai+1aj1ai+aj≡1ai+1aj,即这两个数的和的逆元等于这两个数的逆元的和,注意0没有逆元 Input 第一行一整数TT表示用例组数,每组用例首先输入一整数nn表示序列长度和一素数pp表示模数,之后输入nn个非负整数a1,-,n(1≤T≤5,1≤n≤2×105,2≤p≤1018,0≤a1,-,n<p)a1…

敌兵布阵 Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 66634    Accepted Submission(s): 28074 Problem Description C国的死对头A国这段时间正在进行军事演习,所以C国间谍头子Derek和他手下Tidy又开始忙乎了.A国在海岸线沿直线布置了N个工兵营地,Derek和Tidy的任务…

/* HDU 6058 - Kanade's sum [ 思维,链表 ] | 2017 Multi-University Training Contest 3 题意: 给出排列 a[N],求所有区间的第k大数之和 N <= 5e5, k <= 80 分析: 先求出每个数的位置pos[]数组 然后维护一个单调链表,按数字从大到小向里面加该数字的位置 即对于i的位置 pos[i] 找到链表中比它大的第一个位置和比它小的第一个位置,将pos[i]加到两个之间 这部分用set实现,复杂度 O(nlog…

http://acm.hdu.edu.cn/showproblem.php?pid=1024 Max Sum Plus Plus Problem Description Now I think you have got an AC in Ignatius.L's "Max Sum" problem. To be a brave ACMer, we always challenge ourselves to more difficult problems. Now you are fac…

Lazy Running Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 524288/524288 K (Java/Others)Total Submission(s): 1384    Accepted Submission(s): 597 Problem Description In HDU, you have to run along the campus for 24 times, or you will fail in…

题目链接: sum Time Limit: 2000/1000 MS (Java/Others)     Memory Limit: 131072/131072 K (Java/Others) Problem Description Given a sequence, you're asked whether there exists a consecutive subsequence whose sum is divisible by m. output YES, otherwise outp…

errors made, boundary conditions, <= vs < , decreasing vs increasing , ++, –, '0'/'1' vs 0/1 prototype of sum, return the starting position of c-style string containing the sum, just like sprintf return number of characters successfully read. p1=sum…