friday那一题。。。

  首先表示在搬进实验室的感觉真的很爽。。。

  看了喵呜在群里满看的ACRush的退役帖很有感触，他说的对，光有感触是不够的。以后还是要认真认真动手动脑！！昨天搬进来以后就打算后空多搞搞usaco，毕竟，教主们都说那个是最适合我们菜鸟的了。。

  昨晚搞了一个晚上的friday这道题，结果是我在VC上运行正确的，提交确错的，况且给出的错误样例和我运行的不一样。。。

上题： 

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Friday the Thirteenth

Is Friday the 13th really an unusual event?

That is, does the 13th of the month land on a Friday less often than on any other day of the week? To answer this question, write a program that will compute the frequency that the 13th of each month lands on Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, and Saturday over a given period of N years. The time period to test will be from January 1, 1900 to December 31, 1900+N-1 for a given number of years, N. N is non-negative and will not exceed 400.

There are few facts you need to know before you can solve this problem:

• January 1, 1900 was on a Monday.
• Thirty days has September, April, June, and November, all the rest have 31 except for February which has 28 except in leap years when it has 29.
• Every year evenly divisible by 4 is a leap year (1992 = 4*498 so 1992 will be a leap year, but the year 1990 is not a leap year)
• The rule above does not hold for century years. Century years divisible by 400 are leap years, all other are not. Thus, the century years 1700, 1800, 1900 and 2100 are not leap years, but 2000 is a leap year.

Do not use any built-in date functions in your computer language.

Don't just precompute the answers, either, please.

PROGRAM NAME: friday

INPUT FORMAT

One line with the integer N.

SAMPLE INPUT (file friday.in)

20

OUTPUT FORMAT

Seven space separated integers on one line. These integers represent the number of times the 13th falls on Saturday, Sunday, Monday, Tuesday, ..., Friday.

SAMPLE OUTPUT (file friday.out)

36 33 34 33 35 35 34

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表示  analysis没有看懂。。。

我是这样子写的：#include <stdio.h> int main() { int i,j,m,n; int data=0,year,month,leap,d1[7]={0},d2[7]={0}; scanf("%d",&n); i=1; for(year=1900;year<=1900+n-1;year++) { leap=0; for(month=1;month<=12;month++) { switch(month) { case 1: case 3: case 5: case 7: case 8: case 10: case 12: for(data=1;data<=31;data++,i++) { i=i%7; if(data==13) d2[i]+=1; } break; case 4: case 6: case 9: case 11: for(data=1;data<=30;data++,++i) { i=i%7; if(data==13) d2[i]+=1; } break; case 2: if(year%4==0) if(year%100!=0) leap=1; if(year%400==0) leap=1; if(leap==1) for(data=1;data<=29;data++,++i) { i=i%7; if(data==13) d2[i]+=1; } else for(data=1;data<=28;data++,++i) { i=i%7; if(data==13) d2[i]+=1; } break; } } } printf("%d %d ",d2[6],d2[0]); for(j=1;j<=4;j++) printf("%d ",d2[j]); printf("%d",d2[5]); printf("/n"); return 0; }

 

  一开始是用的if(i==8) i=1;

后来尝试这换成 i=i%7；就OK 了，可能是在if(i=8) i=1;这个部分会多算一步吧。。