题目传送门 题意:问有多少个区间,其中存在j使得ai + d1 == ai+1(i<j) && ai + d2 == ai+1 (i>j) 构造:用c1[i], c2[i]记录i为标杆左边最多几个符合以及右边最多几个符合,那么i的贡献为(c1[i]+1) * (c2[i] + 1):当d1==d2时,找出符合的连续区间,长度记为cnt,那么贡献为(cnt+1) * cnt / 2. ;;) ; ; ;        ; ;        ;        ;          …

题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=5400 水题 #include<stdio.h> typedef long long LL; const int MAXN = 1e5; LL cnt( int x ){ )/; } int main(){ int n; int d1, d2; int flag; int ct; long long ans; int a[MAXN]; while(~scanf("%d %d %d"…

http://acm.hdu.edu.cn/showproblem.php?pid=5400 Arithmetic Sequence Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 1151    Accepted Submission(s): 501 Problem Description A sequence b1,b2,⋯,bn a…

Problem Description A sequence b1,b2,⋯,bn are called (d1,d2)-arithmetic sequence ≤i≤n) such that ≤j<i),bj+=bj+d1 and =bj+d2. Teacher Mai has a sequence a1,a2,⋯,an. He wants to know how many intervals [l,r](≤l≤r≤n) there are that al,al+,⋯,ar are (d1,d…

主要是要知道它对于等差数列的定义,单个数也可以作为等差数列且一定满足题意,另外就是要算清楚区间与区间的关系,考虑两大类情况,一种是d1区间和d2区间连在一起,另外一种情况就是其余情况. #include<iostream> #include<cstdio> #include<cstring> #define MAXN 100005 long long num[MAXN]; bool tag[MAXN]; using namespace std; long long ge…

链接: http://acm.hdu.edu.cn/showproblem.php?pid=5400 Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 875    Accepted Submission(s): 386 Problem Description A sequence b1,b2,⋯,bn are called (d1,d2)…

Arithmetic Sequence Time Limit: 1 Sec  Memory Limit: 128 MBSubmit: 51  Solved: 19[Submit][Status][Web Board] Description Giving a number sequence A with length n, you should choosingm numbers from A(ignore the order) which can form an arithmetic sequ…

Given an array A of integers, return the length of the longest arithmetic subsequence in A. Recall that a subsequence of A is a list A[i_1], A[i_2], ..., A[i_k]with 0 <= i_1 < i_2 < ... < i_k <= A.length - 1, and that a sequence B is arithm…

Arithmetic Sequence Time Limit: 1 Sec  Memory Limit: 128 MBSubmit: 1810  Solved: 311[Submit][Status][Web Board] Description Giving a number sequence A with length n, you should choosing m numbers from A(ignore the order) which can form an arithmetic…

1020: Arithmetic Sequence Time Limit: 1 Sec  Memory Limit: 128 MB Submit:  ->打开链接<- Description Giving a number sequence A with length n, you should choosing m numbers from A(ignore the order) which can form an arithmetic sequence and make m as larg…