Little Victor and Set 其他都很好求, 只有k == 3的时候很难受.. 我们找到第一个不大于l的 t, 答案为 l, 3 * t, (3 * t) ^ l 感觉好像是对的, 感觉又不会证明, 啊, 我好菜啊. #include<bits/stdc++.h> #define LL long long #define fi first #define se second #define mk make_pair #define PLL pair<LL, LL> #…

D. Little Victor and Set time limit per test:1 second memory limit per test:256 megabytes input:standard input output:standard output Little Victor adores the sets theory. Let us remind you that a set is a group of numbers where all numbers are pairw…

题意:从区间[L,R]中选取不多于k个数,使这些数异或和尽量小,输出最小异或和以及选取的那些数. 解法:分类讨论. 设选取k个数. 1. k=4的时候如果区间长度>=4且L是偶数,那么可以构造四个数(L,L+1,L+2,L+3),这样的话(L^(L+1)) ^ ((L+2)^(L+3)) = 0,最优 如果L不是偶数,那么看从L+1到R有没有四个数,如果有则取该四个数,否则最小异或和达不到0,也达不到1了,不再考虑k=4,k=3时还有可能等于0,所以转到k=3 2. k=3时,要使异或和为0,那…

最近的CF几乎都没打,感觉挺水的一个题,不过自己仿佛状态不在,看题解才知道做法. 输入l, r, k (1 ≤ l ≤ r ≤ 1012; 1 ≤ k ≤ min(106, r - l + 1)). 从[l,r]选至多k个数使得选出的数的异或值最小,输出最小异或值和方案. 分类讨论,首先如果r-l+1<=4,枚举集合解决之. 先面讨论r-l+1>=5的情况: 此时有至少5个数可以选择,故至少有连续的4个数满足2x,2x+1,2x+2,2x+3. k==1时显然方案为{l}.k==2时,显然方案…

Description Little Victor adores the sets theory. Let us remind you that a set is a group of numbers where all numbers are pairwise distinct. Today Victor wants to find a set of integers S that has the following properties: for all x the following in…

题目链接:http://codeforces.com/contest/984 A. Game time limit per test:2 seconds memory limit per test:512 megabytes input:standard input output:standard output Two players play a game. Initially there are nn integers a1,a2,…,ana1,a2,…,an written on the…

暴力+构造 If r - l ≤ 4 we can all subsets of size not greater than k. Else, if k = 1, obviously that answer is l. If k = 2, answer is 1, because xor of numbers 2x and 2x + 1 equls 1. If k ≥ 4 answer is 0 because xor of to pairs with xor 1 is 0. If k = 3,…

题意:定义,对于a数组的一个子区间[l,r],f[l,r]定义为对该子区间执行f操作的值.显然,有f[l,r]=f[l,r-1] xor f[l+1,r].又定义ans[l,r]为满足l<=i<=j<=r的f[i,j]的最大值.多次询问你某些区间的ans值. ans=max(f[l,r],ans[l,r-1],ans[l+1,r]),直接递推即可. #include<cstdio> #include<algorithm> using namespace std;…

题意:给你一个分数,问你在b进制下能否化成有限小数. 条件:p/q假如已是既约分数,那么如果q的质因数分解集合是b的子集,就可以化成有限小数,否则不能. 参见代码:反复从q中除去b和q的公因子部分,并缩小该公因子,继续尝试.直到q没有和b的公共因子为止,如果q变成了1,那么有限,否则无限. #include<cstdio> #include<algorithm> using namespace std; typedef long long ll; int T; ll q,p,b;…

Codeforces Round #262 (Div. 2) 1004 D. Little Victor and Set time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Little Victor adores the sets theory. Let us remind you that a set is a group of…