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一个日历问题的C语言,python和Javascript的实现
今天看到一个很有趣的题目,题目描述如下:
根据下列信息计算在1901年1月1日至2000年12月31日间共有多少个星期天落在每月的第一天上?
a) 1900.1.1是星期一
b) 1月,3月,5月,7月,8月,10月和12月是31天
c) 4月,6月,9月和11月是30天
d) 2月是28天,在闰年是29天
e) 公元年数能被4整除且又不能被100整除是闰年
f) 能直接被400整除也是闰年
以下是C语言实现版本:
#include <stdio.h> #include <stdbool.h> bool isLeapYear(int year); // start is the weekday of 1st, January // return the num of the first day of each month // is Sunday. // the start will change into the next year int getYearNum(int* start, int year); // Num of days of each month int days[13] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; int leapdays[13] = {0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; int main(void) { int sum = 0; int start = 1901; int end = 2000; int startWeek = 1; int startYear = 1900; int i; for (i = 1; i < 13; ++i) days[i] += days[i - 1]; for (i = 1; i < 13; ++i) leapdays[i] += leapdays[i - 1]; for (i = startYear; i < start; ++i) getYearNum(&startWeek, i); for (i = start; i <= end; ++i) sum += getYearNum(&startWeek, i); printf("%d\n", sum); return 0; } bool isLeapYear(int year) { if (year % 4 == 0 && year % 100 != 0) return true; else if (year % 400 == 0) return true; return false; } int getYearNum(int* start, int year) { int i; int count = 0; int yeardays; if (isLeapYear(year)) { yeardays = 366; for (i = 0; i < 12; ++i) if ((leapdays[i] % 7 + *start)%7 == 0) ++count; } else { yeardays = 365; for (i = 0; i < 12; ++i) if ((days[i] % 7 + *start)%7 == 0) ++count; } *start = (yeardays % 7 + *start)%7; return count; }下来是最简单的python:
import calendar sum = 0 startYear = 1901 endYear = 2000 for year in xrange(startYear, endYear + 1): for month in xrange(1, 13): if calendar.monthcalendar(year, month)[0].index(1) == 6: sum = sum + 1 print sum
最近对于JavaScript的网页脚本有点感兴趣,就试着用JavaScript实现了一下,感觉不错,有可视化和跨平台性:
<!DOCTYPE html> <html lang="zh-cn"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1"> <title>问题2的解答:Javascript版本</title> </head> <body> <script type="text/javascript"> yearTest = /^[1-9]\d{3}$/; days = new Array(0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31); leapdays = new Array(0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31); for (var i = 1; i < days.length; i++) days[i] += days[i - 1]; for (var i = 1; i < leapdays.length; i++) leapdays[i] += leapdays[i - 1]; sum = 0; function isLeap(year) { if (!yearTest.test(year)) return false; if (year % 4 == 0 && year % 100 != 0) return true; if (year % 400 == 0) return true; return false; } startWeek = 1; totalDays = 365; function getResultOfYear(year) { var sum = 0; if (isLeap(year)) { totalDays = 366; for (var i = 0; i < leapdays.length - 1; i++) { if ((leapdays[i] % 7 + startWeek) % 7 == 0) { //alert("year: " + year + " month: " + (i + 1)); sum++; } } startWeek = (totalDays % 7 + startWeek) % 7; } else { totalDays = 365; for (var i = 0; i < days.length - 1; i++) { if ((days[i] % 7 + startWeek) % 7 == 0) sum++; } startWeek = (totalDays % 7 + startWeek) % 7; } return sum; } function main() { var startYear=document.getElementById("startText").value.replace(/(^\s+)|(\s+$)/g,''); if (startYear == "" || !yearTest.test(startYear)) { alert("不合法的起始年份!"); return; } if (startYear < 1900) { alert("起始年份必须大于等于1900!"); return; } var endYear = document.getElementById("endText").value.replace(/(^\s+)|(\s+$)/g,''); if (endYear == "" || !yearTest.test(endYear)) { alert("不合法的终止年份!"); return; } if (endYear < startYear) { alert("终止年份必须大于等于起始年份!"); return; } sum = 0; startWeek = 1; for (i = 1900; i < startYear; i++) getResultOfYear(i); for (i = startYear; i <= endYear; i++) sum += getResultOfYear(i); document.getElementById("resultText").innerHTML = "从" + startYear + "年1月1日到" + endYear + "年12月23日有<b>" + sum + "</b>个月的1日是周日。"; } </script> 请输入起始年份: <input type="text" id="startText" autofocus onkeydown= "if(event.keyCode==13){endText.focus()}"> <br/> 请输入终止年份: <input type="text" id="endText" onkeydown= "if(event.keyCode==13){ok.click()}"> <br/> <button id="ok" onclick="main()">确定</button> <br/> <p id="resultText"></p> </body> </html>
JavaScript在手机上的效果如下:
OK,一个问题,多种语言,各有优劣。同时用多种语言是一种很不错的体验。
一个日历问题的C语言,python和Javascript的实现
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