传送门 怎么说呢,想了几个小时没做出来实在可惜. \(\color{Red}{首先肯定想到暴力嘛!但是x定值有那么多值可以取,怎么办呢?}\) 但是题目中有一个很关键的条件 \[a[i]>=1\&\&a[i]<=k \] 所以,在最坏情况下我们的答案会是\(n/2-s.(s为\frac{n}{2}对数中和为k+1的总数)\) \(\color{Purple}{为什么?因为不管怎样,对于所有的\frac{n}{2}对数,我都可以改变一个数使得定值变成K+1.}\) \[若改变一个…

题意:给你一个长度为偶数n的数组,每次可以将一个元素修改为不大于k的值,要求每个a[i]+a[n-i+1]都相等,求最少操作多少次 题解:假设每一对的和都为sum,小的记为mn,大的记为mx;         枚举[2,2*k]的所有数x:            我们对每一对相应的数考虑,有三种情况:改一个数,改两个数,不改      1.改一个数:当x∈[mn+1,mx+k];          ==>b[mn+1]+,1,b[mx+k+1]-1; 2.该两个数:当x∈[2,mn] || [m…

题目链接:Codeforces 486C Palindrome Transformation 题目大意:给定一个字符串,长度N.指针位置P,问说最少花多少步将字符串变成回文串. 解题思路:事实上仅仅要是对称位置不同样的.那么指针肯定要先移动到这里,改动字符仅仅须要考虑两种方向哪种更优即 可. 然后将全部须要到达的位置跳出来.贪心处理. #include <cstdio> #include <cstring> #include <cstdlib> #include <…

点击打开链接 C. Palindrome Transformation time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Nam is playing with a string on his computer. The string consists of n lowercase English letters. It is m…

Special Thanks: Jane Alam Jan*At moment in University of Texas at San Antonio - USA You will be given n integers A1A2A3...An. Find a permutation of these n integers so that summation of the absolute differences between adjacent elements is maximized.…

C. Palindrome Transformation     Nam is playing with a string on his computer. The string consists of n lowercase English letters. It is meaningless, so Nam decided to make the string more beautiful, that is to make it be a palindrome by using 4 arro…

C. Palindrome Transformation time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Nam is playing with a string on his computer. The string consists of n lowercase English letters. It is meaningl…

题意:给定一个字符串,求一个最长的回回文子串,多解输出第一个. 析:把字符串翻转然后放到后面去,中间用另一个字符隔开,然后枚举每一个回文串的的位置,对第 i 个位置,那么对应着第二个串的最长公共前缀, 求最长公共子串,可以用RMQ解决. 代码如下: #pragma comment(linker, "/STACK:1024000000,1024000000") #include <cstdio> #include <string> #include <cst…

Kiki likes traveling. One day she finds a magic lamp, unfortunately the genie in the lamp is not so kind. Kiki must answer a question, and then the genie will realize one of her dreams. The question is: give you an integer, you are allowed to delete…

题目链接:http://codeforces.com/contest/602/problem/B 题意 :给出一个含有 n 个数的区间,要求找出一个最大的连续子区间使得这个子区间的最大值和最小值的差值不超过 1 ,最后输出这个子区间的长度. 分析 :我们可以根据区间的最值之差利用尺取的方法来找出答案=> if(差值>1) Left++; else Right++; 然后每一次右端点+1就更新一次答案直到右端点到达 n .在这里我们需要找出区间最值,也就是经典的RMQ问题,可以利用ST算法模板进…