http://codeforces.com/contest/1092/problem/D1

Vova's family is building the Great Vova Wall (named by Vova himself). Vova's parents, grandparents, grand-grandparents contributed to it. Now it's totally up to Vova to put the finishing touches.

The current state of the wall can be respresented by a sequence aa of nn integers, with aiai being the height of the ii-th part of the wall.

Vova can only use 2×12×1 bricks to put in the wall (he has infinite supply of them, however).

Vova can put bricks horizontally on the neighboring parts of the wall of equal height. It means that if for some ii the current height of part iiis the same as for part i+1i+1, then Vova can put a brick there and thus increase both heights by 1. Obviously, Vova can't put bricks in such a way that its parts turn out to be off the borders (to the left of part 11 of the wall or to the right of part nn of it).

The next paragraph is specific to the version 1 of the problem.

Vova can also put bricks vertically. That means increasing height of any part of the wall by 2.

Vova is a perfectionist, so he considers the wall completed when:

  • all parts of the wall has the same height;
  • the wall has no empty spaces inside it.

Can Vova complete the wall using any amount of bricks (possibly zero)?

Input

The first line contains a single integer nn (1≤n≤2⋅1051≤n≤2⋅105) — the number of parts in the wall.

The second line contains nn integers a1,a2,…,ana1,a2,…,an (1≤ai≤1091≤ai≤109) — the initial heights of the parts of the wall.

Output

Print "YES" if Vova can complete the wall using any amount of bricks (possibly zero).

Print "NO" otherwise.

Examples
input

Copy
5
2 1 1 2 5
output

Copy
YES
input

Copy
3
4 5 3
output

Copy
YES
input

Copy
2
10 10
output

Copy
YES
input

Copy
3
1 2 3
output

Copy
NO
Note

In the first example Vova can put a brick on parts 2 and 3 to make the wall [2,2,2,2,5][2,2,2,2,5] and then put 3 bricks on parts 1 and 2 and 3 bricks on parts 3 and 4 to make it [5,5,5,5,5][5,5,5,5,5].

In the second example Vova can put a brick vertically on part 3 to make the wall [4,5,5][4,5,5], then horizontally on parts 2 and 3 to make it [4,6,6][4,6,6] and then vertically on part 1 to make it [6,6,6][6,6,6].

In the third example the wall is already complete.

代码:

#include <bits/stdc++.h>
using namespace std; int N;
stack<int> s; int main() {
scanf("%d", &N);
for(int i = 0; i < N; i ++) {
int x;
scanf("%d", &x);
if(s.empty())
s.push(x);
else {
if(abs(s.top() - x) % 2)
s.push(x);
else s.pop();
}
} if(s.size() > 1) printf("NO\n");
else printf("YES\n");
return 0;
}

  相邻的两个墙的高度差是 2 的倍数就可以了

CodeForces Round #527 (Div3) D1. Great Vova Wall (Version 1)的更多相关文章

  1. CodeForces Round #527 (Div3) D2. Great Vova Wall (Version 2)

    http://codeforces.com/contest/1092/problem/D2 Vova's family is building the Great Vova Wall (named b ...

  2. Codeforces Round #527 (Div. 3) D1. Great Vova Wall (Version 1) 【思维】

    传送门:http://codeforces.com/contest/1092/problem/D1 D1. Great Vova Wall (Version 1) time limit per tes ...

  3. CodeForces Round #527 (Div3) B. Teams Forming

    http://codeforces.com/contest/1092/problem/B There are nn students in a university. The number of st ...

  4. CodeForces Round #527 (Div3) C. Prefixes and Suffixes

    http://codeforces.com/contest/1092/problem/C Ivan wants to play a game with you. He picked some stri ...

  5. CodeForces Round #527 (Div3) A. Uniform String

    http://codeforces.com/contest/1092/problem/A You are given two integers nn and kk. Your task is to c ...

  6. D1. Great Vova Wall (Version 1)

    链接 [https://codeforces.com/contest/1092/problem/D1] 题意 给你n个位置墙的高度,现在你有2×1 砖块,你可以竖直或者水平放置 问你是否可以使得所有位 ...

  7. Codeforces Round #602 Div2 D1. Optimal Subsequences (Easy Version)

    题意:给你一个数组a,询问m次,每次返回长度为k的和最大的子序列(要求字典序最小)的pos位置上的数字. 题解:和最大的子序列很简单,排个序就行,但是题目要求字典序最小,那我们在刚开始的时候先记录每个 ...

  8. Codeforces Round #527 (Div. 3) ABCDEF题解

    Codeforces Round #527 (Div. 3) 题解 题目总链接:https://codeforces.com/contest/1092 A. Uniform String 题意: 输入 ...

  9. Codeforces Round #527 (Div. 3)

    一场div3... 由于不计rating,所以打的比较浪,zhy直接开了个小号来掉分,于是他AK做出来了许多神仙题,但是在每一个程序里都是这么写的: 但是..sbzhy每题交了两次,第一遍都是对的,结 ...

随机推荐

  1. LFS搭建第一天补充

    1.选择lfs的iso 2.启动虚拟机,进入以下界面直接按回车键 3. 选择下面的时间 4.直接默认本地时间 5.语言格式选择UTF-8 6.默认 7.直接回车,进入系统 8.对hda盘进行分区,我分 ...

  2. C语言堆排序

    堆是一种类似二叉树的数据结构,分为最大堆和最小堆,最大堆得定义是当前节点必须大于左右子节点,堆中所有节点都要符合这个定义.最小堆反之.这一点不同于二叉树排序.假设有数组int a[10] = {90, ...

  3. Java线程等待与唤醒

    class ThreadA extends Thread{ public ThreadA(String name) { super(name); } public void run() { synch ...

  4. freeradius+xl2tp+mysql整合

    freeradius+xl2tp+mysql整合 搭了5个小时,可以说是入门到精通了.首先请确认你已经搭建好L2TP,并可以正常使用.  如何在Ubuntu下配置L2TP VPN L2TP使用radi ...

  5. 20155227 2016-2017-2 《Java程序设计》第十周学习总结

    20155227 2016-2017-2 <Java程序设计>第十周学习总结 教材学习内容总结 Java的网络编程 网络编程 就是在两个或两个以上的设备(例如计算机)之间传输数据.程序员所 ...

  6. 20155310 2016-2017-2 《Java程序设计》第十周学习总结

    20155310 2016-2017-2 <Java程序设计>第十周学习总结 教材学习内容总结 网络编程 •网络编程就是在两个或两个以上的设备(例如计算机)之间传输数据.程序员所作的事情就 ...

  7. kali更新源相关 -- 没有release文件、签名无效、404

    kali更新源相关 -- 没有release文件.签名无效.404 这个随笔主要是处理Mac下使用VMare虚拟机安装Kali时候我遇到的一些关于更新源的问题 (因为本人为了这个问题折腾了四五个小时, ...

  8. win32api 找不到指定的模块

    pywin32 安装后 import win32api 出现ImportError: DLL load failed: 找不到指定的模块 解决方法: 拷贝 C:\Python26\Lib\site-p ...

  9. sqlserver安装遇到的问题——1

    SQL Server安装过无数次,今天第一次遇到这样的问题 一.问题消息复制出来是这样的 TITLE: Microsoft SQL Server 2008 R2 安装程序--------------- ...

  10. 420. Count and Say【LintCode java】

    Description The count-and-say sequence is the sequence of integers beginning as follows: 1, 11, 21, ...