1042 Shuffling Machine (20分) 思路分析

题目

Shuffling is a procedure used to randomize a deck of playing cards. Because standard shuffling techniques are seen as weak, and in order to avoid “inside jobs” where employees collaborate with gamblers by performing inadequate shuffles, many casinos employ automatic shuffling machines. Your task is to simulate a shuffling machine.

The machine shuffles a deck of 54 cards according to a given random order and repeats for a given number of times. It is assumed that the initial status of a card deck is in the following order:

S1, S2, …, S13,
H1, H2, …, H13,
C1, C2, …, C13,
D1, D2, …, D13,
J1, J2

where “S” stands for “Spade”, “H” for “Heart”, “C” for “Club”, “D” for “Diamond”, and “J” for “Joker”. A given order is a permutation of distinct integers in [1, 54]. If the number at the i-th position is j, it means to move the card from position i to position j. For example, suppose we only have 5 cards: S3, H5, C1, D13 and J2. Given a shuffling order {4, 2, 5, 3, 1}, the result will be: J2, H5, D13, S3, C1. If we are to repeat the shuffling again, the result will be: C1, H5, S3, J2, D13.
Input Specification:

Each input file contains one test case. For each case, the first line contains a positive integer K (≤20) which is the number of repeat times. Then the next line contains the given order. All the numbers in a line are separated by a space.
Output Specification:

For each test case, print the shuffling results in one line. All the cards are separated by a space, and there must be no extra space at the end of the line.
Sample Input:

2
36 52 37 38 3 39 40 53 54 41 11 12 13 42 43 44 2 4 23 24 25 26 27 6 7 8 48 49 50 51 9 10 14 15 16 5 17 18 19 1 20 21 22 28 29 30 31 32 33 34 35 45 46 47

Sample Output:

S7 C11 C10 C12 S1 H7 H8 H9 D8 D9 S11 S12 S13 D10 D11 D12 S3 S4 S6 S10 H1 H2 C13 D2 D3 D4 H6 H3 D13 J1 J2 C1 C2 C3 C4 D1 S5 H5 H11 H12 C6 C7 C8 C9 S2 S8 S9 H10 D5 D6 D7 H4 H13 C5

题目大意

这台机器按照给定的随机顺序洗牌一副54张牌，并重复一定次数。假设卡片组的初始状态如下：

S1，S2，…，S13，

H1，H2，…，H13，

C1，C2，…，C13，

D1，D2，…，D13，

J1、J2

其中“S”代表“黑桃”，“H”代表“心”，“C”代表“俱乐部”，“D”代表“钻石”，“J”代表“小丑”。给定的顺序是[1，54]中不同整数的排列。如果第i个位置的数字是j，则意味着将卡从位置i移动到位置j。例如，假设我们只有5张卡：S3、H5、C1、D13和J2。给定洗牌顺序{4，2，5，3，1}，结果将是：J2，H5，D13，S3，C1。如果我们再次重复洗牌，结果将是：C1、H5、S3、J2、D13。

输入规格：

每个输入文件包含一个测试用例。对于每种情况，第一行包含一个正整数K（≤20），它是重复次数。下一行包含给定的顺序。一行中的所有数字都用空格隔开。

输出规格：

对于每个测试用例，在一行中打印洗牌结果。所有的卡片都被一个空格隔开，行的末尾不能有多余的空格。

样本输入：

2

36 52 37 38 3 39 40 53 41 11 12 42 43 44 2 4 24 25 26 6 7 8 49 50 51 10 15 16 5 18 19 21 28 30 32 34 45 47

样本输出：

S7 C11 C10 C12 S1 H7 H8 H9 D8 D9 S11 S12 S13 D10 D11 S3 S4 S6 S10 H1 H2 C13 D3 D4 H6 H6 D3 J1 J2 C2 C3 C4 D1 S5 H1 H12 C6 C8 C9 S2 S8 S9 H10 D5 D6 D7 H4 H13 C5

分析

模拟类型的题目。
这个题就是模拟一个洗牌机n次洗牌的过程。本质上就是n次map映射的过程。

代码

#include<iostream>
#include<string>
using namespace std;
int main()
{
	string start[55] = { "","S1","S2","S3","S4","S5","S6","S7","S8","S9","S10","S11","S12","S13","H1","H2","H3","H4","H5","H6","H7","H8","H9","H10","H11","H12","H13","C1","C2","C3","C4","C5","C6","C7","C8","C9","C10","C11","C12","C13","D1","D2","D3","D4","D5","D6","D7","D8","D9","D10","D11","D12","D13","J1","J2" };
	int next[55];
	string end[55];
	int n;
	cin >> n;
	for (int i = 1; i <= 54; i++) cin >> next[i];//输入牌操作后的位置
	for (int i = 0; i < n; i++)
	{
		for (int j = 1; j < 55; j++) end[next[j]] = start[j];//将第j个牌放到位置next[j]上
		for (int j = 1; j < 55; j++) start[j] = end[j];//更新，以便下一次洗牌。
	}
	cout << end[1];
	for (int i = 2; i < 55; i++) cout << " " << end[i];
	return 0;
}

反思

这道题是模拟类型的好题目，51线上模拟赛第一题就是这样的题，但是难度远不如这个。