hrbust1001 Probability One

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本文解析了一道经典的猜数字游戏模拟题，介绍了游戏规则及编程实现方法。通过简单的数学运算，可以预测并验证朋友心中所想的数字。

原题网址：http://acm.hrbust.edu.cn/index.php?m=ProblemSet&a=showProblem&problem_id=1001

Probability One

Time Limit: 1000 MS

Memory Limit: 65536 K

Total Submit: 3209(1356 users)

Total Accepted: 1412(1213 users)

Rating:

Special Judge: No

Description

     Number guessing is a popular game between elementary-school kids. Teachers encourage pupils to play the game as it enhances their arithmetic skills, logical thinking, and following-up simple procedures. We think that, most probably, you too will master in few minutes. Here’s one example of how you too can play this game: Ask a friend to think of a number, let’s call it n
     0.
     
 Then:
     
 1. Ask your friend to compute n
     1 = 3 * n
     0 and to tell you if n1 is even or odd.
     
 2. If n
     1 is even, ask your friend to compute n
     2 = n
     1/2. If, otherwise, n
     1 was odd then let your friend compute n
     2 = (n
     1 + 1)/2.
     
 3. Now ask your friend to calculate n
     3 = 3 * n
     2.
     
 4. Ask your friend to tell tell you the result of n
     4 = n
     3/9. (n
     4 is the quotient of the division operation. In computer lingo, ’/’ is the integer-division operator.)
     
 5. Now you can simply reveal the original number by calculating n
     0 = 2 * n
     4 if n
     1 was even, or n
     0 = 2 * n
     4 + 1 otherwise.
     
 Here’s an example that you can follow: If n
     0 = 37, then n
     1 = 111 which is odd. Now we can calculate n
     2 = 56, n
     3= 168, and n
     4 = 18, which is what your friend will tell you. Doing the calculation 2 × n
     4 + 1 = 37 reveals n
     0.
     
  
    

Input

     Your program will be tested on one or more test cases. Each test case is made of a single positive number (0 < n
     0 < 1, 000, 000).
     
 The last line of the input file has a single zero (which is not part of the test cases.)

Output

     For each test case, print the following line:
     
 k. B Q
     
 Where k is the test case number (starting at one,) B is either ’even’ or ’odd’ (without the quotes) depending on your friend’s answer in step 1. Q is your friend’s answer to step 4.
     
 Note: There is a blank space before B.

Sample Input

 37
 38
 0

Sample Output

 1. odd 18
 2. even 19

一道模拟基础题，按照题目步奏来，注意输入和输出与第一题的变化。

#include<stdio.h>

int main()
{
    int n0;
    int Case = 1;
    while(scanf("%d",&n0) != EOF){
        if(n0 == 0){
            return 0;
        }

        int n1 = 3*n0;
        bool flag;
        if(n1%2 == 1){
            flag = true;//奇数
        }
        else{
            flag = false;//偶数
        }

        int n2;
        if(!flag){
            n2 = n1/2;
        }
        else{
            n2 = (n1+1)/2;
        }

        int n3 = 3*n2;

        int n4 = n3/9;

        if(!flag)
            printf("%d. even %d\n",Case++,n4);
        else
            printf("%d. odd %d\n",Case++,n4);
    }
    return 0;
}