【codeforces 764B】Timofey and cubes
time limit per test1 second
memory limit per test256 megabytes
inputstandard input
outputstandard output
Young Timofey has a birthday today! He got kit of n cubes as a birthday present from his parents. Every cube has a number ai, which is written on it. Timofey put all the cubes in a row and went to unpack other presents.
In this time, Timofey’s elder brother, Dima reordered the cubes using the following rule. Suppose the cubes are numbered from 1 to n in their order. Dima performs several steps, on step i he reverses the segment of cubes from i-th to (n - i + 1)-th. He does this while i ≤ n - i + 1.
After performing the operations Dima went away, being very proud of himself. When Timofey returned to his cubes, he understood that their order was changed. Help Timofey as fast as you can and save the holiday — restore the initial order of the cubes using information of their current location.
Input
The first line contains single integer n (1 ≤ n ≤ 2·105) — the number of cubes.
The second line contains n integers a1, a2, …, an ( - 109 ≤ ai ≤ 109), where ai is the number written on the i-th cube after Dima has changed their order.
Output
Print n integers, separated by spaces — the numbers written on the cubes in their initial order.
It can be shown that the answer is unique.
Examples
input
7
4 3 7 6 9 1 2
output
2 3 9 6 7 1 4
input
8
6 1 4 2 5 6 9 2
output
2 1 6 2 5 4 9 6
Note
Consider the first sample.
At the begining row was [2, 3, 9, 6, 7, 1, 4].
After first operation row was [4, 1, 7, 6, 9, 3, 2].
After second operation row was [4, 3, 9, 6, 7, 1, 2].
After third operation row was [4, 3, 7, 6, 9, 1, 2].
At fourth operation we reverse just middle element, so nothing has changed. The final row is [4, 3, 7, 6, 9, 1, 2]. So the answer for this case is row [2, 3, 9, 6, 7, 1, 4].
【题目链接】:http://codeforces.com/contest/764/problem/B
【题解】
如果从初始数列到目标数列
操作依次为
[1..倒1]翻转
[2..倒2]翻转
[3..倒3]翻转
…
[i..倒i]翻转
前面的翻转区间覆盖了后面的翻转区间;
所以如果是偶数次翻转,那么翻转的区间的两端那个元素是不会改变顺序的;还是原来的位置;
而如果是奇数次翻转,两端的元素就会交换位置;
根据这个规则处理出原序列就好;
(reverse函数和sort函数都是左闭右开区间…..)
【完整代码】
#include <bits/stdc++.h>
using namespace std;
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
#define LL long long
#define rep1(i,a,b) for (int i = a;i <= b;i++)
#define rep2(i,a,b) for (int i = a;i >= b;i--)
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define rei(x) scanf("%d",&x)
#define rel(x) scanf("%I64d",&x)
typedef pair<int,int> pii;
typedef pair<LL,LL> pll;
const int dx[9] = {0,1,-1,0,0,-1,-1,1,1};
const int dy[9] = {0,0,0,-1,1,-1,1,-1,1};
const double pi = acos(-1.0);
const int MAXN = 2e5+100;
int a[MAXN];
int n;
int main()
{
//freopen("F:\\rush.txt","r",stdin);
rei(n);
rep1(i,1,n)
rei(a[i]);
int cnt = 0;
for (int i = 1;i<=n;i++)
{
int j = n-i+1;
if (i <= j)
{
cnt++;
if (cnt&1)
swap(a[i],a[j]);
}
}
rep1(i,1,n)
{
printf("%d",a[i]);
if (i==n)
puts("");
else
putchar(' ');
}
return 0;
}
【codeforces 764B】Timofey and cubes的更多相关文章
- 【codeforces 764C】Timofey and a tree
time limit per test2 seconds memory limit per test256 megabytes inputstandard input outputstandard o ...
- 【codeforces 764D】Timofey and rectangles
[题目链接]:http://codeforces.com/contest/764/problem/D [题意] 给你n个矩形,以左下角坐标和右上角坐标的形式给出; (保证矩形的边长为奇数) 问你有没有 ...
- 【75.28%】【codeforces 764B】Decoding
time limit per test1 second memory limit per test256 megabytes inputstandard input outputstandard ou ...
- 【codeforces 415D】Mashmokh and ACM(普通dp)
[codeforces 415D]Mashmokh and ACM 题意:美丽数列定义:对于数列中的每一个i都满足:arr[i+1]%arr[i]==0 输入n,k(1<=n,k<=200 ...
- 【codeforces 764A】Taymyr is calling you
time limit per test1 second memory limit per test256 megabytes inputstandard input outputstandard ou ...
- 【codeforces 707E】Garlands
[题目链接]:http://codeforces.com/contest/707/problem/E [题意] 给你一个n*m的方阵; 里面有k个联通块; 这k个联通块,每个连通块里面都是灯; 给你q ...
- 【codeforces 707C】Pythagorean Triples
[题目链接]:http://codeforces.com/contest/707/problem/C [题意] 给你一个数字n; 问你这个数字是不是某个三角形的一条边; 如果是让你输出另外两条边的大小 ...
- 【codeforces 709D】Recover the String
[题目链接]:http://codeforces.com/problemset/problem/709/D [题意] 给你一个序列; 给出01子列和10子列和00子列以及11子列的个数; 然后让你输出 ...
- 【codeforces 709B】Checkpoints
[题目链接]:http://codeforces.com/contest/709/problem/B [题意] 让你从起点开始走过n-1个点(至少n-1个) 问你最少走多远; [题解] 肯定不多走啊; ...
随机推荐
- delete records in table A not in table B
转)A.B两表,找出ID字段中,存在A表,但是不存在B表的数据.A表总共13w数据,去重后大约3W条数据,B表有2W条数据,且B表的ID字段有索引. 方法一 使用 not in ,容易理解,效率低 ...
- vue页面跳转传参
跳转页 this.$router.push({name:'路由命名',params:{参数名:参数值,参数名:参数值}}) 接收页 this.$route.params.参数名
- 纯CSS3绘制的黑色图标按钮组合
在线演示 本地下载
- JavaScript中的this关键字的几种用法
JS 里的 this 在 function 内部被创建 指向调用时所在函数所绑定的对象(拗口) this 不能被赋值,但可以被 call/apply 改变 1. this 和构造函数 function ...
- CF789D Mike and distribution
题目连接 一道人类智慧题.... 这道题目可以转化为在a,b中的选出一些位置,使得这些位置处的值加起来大于没有选的位置的值 我们按照a的权值排序,选择第一个元素,其与元素两两分组,每组选择b更大的那一 ...
- 通过反射 往泛型Integer的集合里添加String 类型的数据 Day25
package com.sxt.method1; import java.lang.reflect.Method; /* * 需求:通过反射 往泛型Integer的集合里添加String 类型的数据 ...
- Oracle 11g Pivot函数实现行转列
先上语法规范: SELECT .... FROM <table-expr> PIVOT ( aggregate-function(<column>) FOR <pivot ...
- React 从零搭建项目 使用 create-react-app脚手架
一.安装 npm install -g create-react-app 版本校验:create-react-app --version 二.创建项目 create-react-app指令默认调用np ...
- Josephus问题Java实现
package com.qingfeng; /** * @author Administrator * 功能:约瑟夫问题: * 设编号分别为:1,2,...,n的n个人围坐一圈. * 约定序号为k(1 ...
- 11-1 css属性选择器
一 基础选择器 标签选择器:选择的标签的‘共性’,而不是特性 div{}.ul{}.ol{}.form{} 类选择器:.box{} id选择器:#box{} 只能选择器的特性,主要是为了js *通配符 ...