HDU 1079 Calendar Game（规律博弈）

题目链接：
https://cn.vjudge.net/problem/HDU-1079

题目：

Adam and Eve enter this year’s ACM International Collegiate Programming Contest. Last night, they played the Calendar Game, in celebration of this contest. This game consists of the dates from January 1, 1900 to November 4, 2001, the contest day. The game starts by randomly choosing a date from this interval. Then, the players, Adam and Eve, make moves in their turn with Adam moving first: Adam, Eve, Adam, Eve, etc. There is only one rule for moves and it is simple: from a current date, a player in his/her turn can move either to the next calendar date or the same day of the next month. When the next month does not have the same day, the player moves only to the next calendar date. For example, from December 19, 1924, you can move either to December 20, 1924, the next calendar date, or January 19, 1925, the same day of the next month. From January 31 2001, however, you can move only to February 1, 2001, because February 31, 2001 is invalid.

A player wins the game when he/she exactly reaches the date of November 4, 2001. If a player moves to a date after November 4, 2001, he/she looses the game.

Write a program that decides whether, given an initial date, Adam, the first mover, has a winning strategy.

For this game, you need to identify leap years, where February has 29 days. In the Gregorian calendar, leap years occur in years exactly divisible by four. So, 1993, 1994, and 1995 are not leap years, while 1992 and 1996 are leap years. Additionally, the years ending with 00 are leap years only if they are divisible by 400. So, 1700, 1800, 1900, 2100, and 2200 are not leap years, while 1600, 2000, and 2400 are leap years.

InputThe input consists of T test cases. The number of test cases (T) is given in the first line of the input. Each test case is written in a line and corresponds to an initial date. The three integers in a line, YYYY MM DD, represent the date of the DD-th day of MM-th month in the year of YYYY. Remember that initial dates are randomly chosen from the interval between January 1, 1900 and November 4, 2001.
OutputPrint exactly one line for each test case. The line should contain the answer "YES" or "NO" to the question of whether Adam has a winning strategy against Eve. Since we have T test cases, your program should output totally T lines of "YES" or "NO".
Sample Input

3 
2001 11 3 
2001 11 2 
2001 10 3 

Sample Output

YES 
NO 
NO 

解题思路：

　　已知两个人的博弈方式只能是days+1或者month+1，可得days+month之和总是在奇数和偶数之间变换，所以目标是取到11+4为奇数，那就必须要面对偶数才能赢。所以当给出的日期是偶数时，先手必赢，奇数时，先手必输，不过有两个特例是，9.30和11.30，他们是奇数，但是他们的两个后继有一个是还是奇数，能造成先手还是面临偶数，所以也行。

 1 #include<cstdio>
 2 
 3 int main()
 4 {
 5     int T;
 6     scanf("%d", &T);
 7     int y, m, d;
 8     while(T--){
 9         scanf("%d%d%d", &y, &m, &d);
10         if((m + d) % 2 == 0 || (d == 30) && (m == 9 || m == 11))
11             printf("YES\n");
12         else
13             printf("NO\n");
14     }
15     return 0;
16 }