B. Odd sum 题目链接:http://codeforces.com/problemset/problem/797/B time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output You are given sequence a1, a2, ..., an of integer numbers of length n. Your ta…

Odd sum CodeForces - 797B 好方法:贪心 贪心2 糟糕(不用动脑)的方法:dp ans[i][0]表示到第i个和为偶数最大,ans[i][1]表示到第i个和为奇数最大. 但是,仍然容易写挂!(注意细节) #include<cstdio> #include<algorithm> #include<cstring> using namespace std; typedef long long LL; LL ans[][]; LL a[]; LL n;…

B. Odd Sum Segments time limit per test3 seconds memory limit per test256 megabytes inputstandard input outputstandard output You are given an array a consisting of n integers a1,a2,-,an. You want to split it into exactly k non-empty non-intersecting…

You are given an array aa consisting of nn integers. In one move, you can choose two indices 1≤i,j≤n1≤i,j≤n such that i≠ji≠j and set ai:=ajai:=aj . You can perform such moves any number of times (possibly, zero). You can choose different indices in d…

https://codeforces.com/problemset/problem/797/B time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output You are given sequence a1, a2, ..., an of integer numbers of length n. Your task is to find s…

题目地址 http://codeforces.com/contest/1196/problem/B B. Odd Sum Segments time limit per test 3 seconds memory limit per test 256 megabytes input standard input output standard output You are given an array aa consisting of nn integers a1,a2,…,ana1,a2,…,…

题目链接:Codeforces 396B On Sum of Fractions 题解来自:http://blog.csdn.net/keshuai19940722/article/details/20076297 题目大意:给出一个n,ans = ∑(2≤i≤n)1/(v(i)*u(i)), v(i)为不大于i的最大素数,u(i)为大于i的最小素数, 求ans,输出以分式形式. 解题思路:一開始看到这道题1e9,暴力是不可能了,没什么思路,后来在纸上列了几项,突然想到高中时候求等差数列时候用到…

B. Odd sum time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output You are given sequence a1, a2, ..., an of integer numbers of length n. Your task is to find such subsequence that its sum is odd a…

codeforces 963A Alternating Sum 题解 计算前 \(k\) 项的和,每 \(k\) 项的和是一个长度为 \((n+1)/k\) ,公比为 \((a^{-1}b)^k\) 的等比数列. 当公比为 \(1\) 时,不能用等比数列求和公式. 什么时候公比为 \(1\) ? 当 \(a=b\) 时,\(a^{-1}b=1(mod\ p)\) 当 \(a=p-b\) 时,\(a^{-1}b=(p-b)^{-1}b=-1(mod\ p)\),如果此时 \(k\) 是偶数,公比就…

codeforces 1217E E. Sum Queries? (线段树 传送门:https://codeforces.com/contest/1217/problem/E 题意: n个数,m次询问 单点修改 询问区间内最小的unbalanced number balanced number定义是,区间内选取数字的和sum sum上的每一位都对应着选取的数上的一位 否则就是unbalanced number 题解: 根据题意 如果区间存在unbalance number,那么一定存在两个数就可…