Codeforces834A The Useless Toy

旋转玩具的方向判断

最新推荐文章于 2019-04-05 09:33:07 发布

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本文介绍了一个简单的算法问题，通过输入玩具的起始和结束位置及旋转时间，判断玩具的旋转方向是顺时针还是逆时针，或者无法确定。使用了C++实现，并通过映射表来快速匹配方向。

$\text{[math]}$

Walking through the streets of Marshmallow City, Slastyona have spotted some merchants selling a kind of useless toy which is very popular nowadays – caramel spinner! Wanting to join the craze, she has immediately bought the strange contraption.

Spinners in Sweetland have the form of V-shaped pieces of caramel. Each spinner can, well, spin around an invisible magic axis. At a specific point in time, a spinner can take 4 positions shown below (each one rotated 90 degrees relative to the previous, with the fourth one followed by the first one):

$\text{[math]}$

After the spinner was spun, it starts its rotation, which is described by a following algorithm: the spinner maintains its position for a second then majestically switches to the next position in clockwise or counter-clockwise order, depending on the direction the spinner was spun in.

Slastyona managed to have spinner rotating for exactly n seconds. Being fascinated by elegance of the process, she completely forgot the direction the spinner was spun in! Lucky for her, she managed to recall the starting position, and wants to deduct the direction given the information she knows. Help her do this.

Input

There are two characters in the first string – the starting and the ending position of a spinner. The position is encoded with one of the following characters: v (ASCII code 118, lowercase v), < (ASCII code 60), ^ (ASCII code 94) or > (ASCII code 62) (see the picture above for reference). Characters are separated by a single space.

In the second strings, a single number n is given (0 ≤ n ≤ 109) – the duration of the rotation.

It is guaranteed that the ending position of a spinner is a result of a n second spin in any of the directions, assuming the given starting position.

Output

Output cw, if the direction is clockwise, ccw – if counter-clockwise, and undefined otherwise.

Examples

input
^ >
1

output
cw

input
< ^
3

output
ccw

input
^ v
6

output
undefined

————————————————————————————————————

题目的意思是给出两个方向和步骤，然后判是怎么判的

思路:先用map存一下4个方向，然后分别判顺逆时针能否达到

#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <algorithm>
#include <cmath>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <vector>
#include <bitset>

using namespace std;

#define ll long long
const int INF = 0x3f3f3f3f;
#define mod 10000007
#define mem(a,b) memset(a,b,sizeof a)

map<char,int>mp;
int main()
{

    mp['^']=0;
    mp['>']=1;
    mp['v']=2;
    mp['<']=3;
    char a,b;
    int n;
    while(cin>>a>>b)
    {
        cin>>n;
        n%=4;

        int x1=mp[a]+n;
        if(x1>3)x1-=4;
        int x2=mp[a]-n;
        if(x2<0)x2+=4;
        if(x1==mp[b]&&x2!=mp[b])
            printf("cw\n");
        else if(x1!=mp[b]&&x2==mp[b])
            printf("ccw\n");
        else
            printf("undefined\n");

    }
    return 0;
}