自測-5 Shuffling Machine (20分)

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

解題思路：
這裏邊第一個考點是Shuffle過程，因爲我們之前學過MapReduce，裏面也有這個Shuffle過程，Shuffle的正常意思是洗牌或弄亂，可能大家更熟悉的是Java API裏的Collections.shuffle(List)方法，它會隨機地打亂參數list裏的元素順序。這道題的意思也是將撲克牌按照麼一種特定順序洗多次，使得撲克牌的順序被打亂，然後就讓我們求打亂後的牌的順序。
可以將撲克牌拆分，字母：S、C、D、J。數字：1—13。三個整型數組分別存放：0–53個數字、洗牌的順序、洗後的順序，洗後字母的確定方法：用其對13整除，根據除數，判斷花色，輸出即可，洗後數字的確定方法：將其值對13求餘，即可算出數字，然後拼接輸出即可。

代碼：

#include <stdio.h>
#include <stdlib.h>

int c[600];
int a[600];
int b[600];

//a[]:S1,S2...   b[]:6,32...  c[]:ans
void shuffle()//洗牌過程
{
    int i,t;
    for(i=1; i<55; i++)
    {
        t = b[i];
        c[t] = a[i];
    }
    for(i=1; i<55; i++)
    {
        a[i] = c[i];
    }
}

void card_init()
{
    int i;
    for(i=1; i<=54; i++)
    {
        a[i] = i;
    }
}

char get_color(int n)
{
    char ch;
    if((n-1)/13 == 0)
    {
        ch = 'S';
    }
    else if((n-1)/13 == 1)
    {
        ch = 'H';
    }
    else if((n-1)/13 == 2)
    {
        ch = 'C';
    }
    else if((n-1)/13 == 3)
    {
        ch = 'D';
    }
    else
    {
        ch = 'J';
    }
    return ch;
}


//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

int main()
{
    int n,i;
    char ch;
    scanf("%d",&n);
    for(i=1; i<=54; i++)
    {
        scanf("%d",&(b[i]));
    }

    card_init();

    for(i=0; i<n; i++)
    {
        shuffle();
    }

    for(i=1; i<=54; i++)
    {
        ch = get_color(c[i]);
        printf("%c",ch);
        printf("%d",(c[i])%13==0?13:(c[i])%13);
        if(i != 54)
        {
            printf(" ");
        }
    }

    return 0;
}

運行結果：