[ GO FOR IT ] 1) 人生の時計

問題：

あなたの一生を24時間にたとえると今日は何時何分何秒ですか？
ただしあなたはあなたの誕生日(a年b月c日)の0時ちょうどに生まれてn歳まで生きる(n歳のときは生きていてn+1歳にはなれない)とし、bとcは一般的な月日の範囲とします。

i) 1990<=a<=2000,n=80のとき、今日は何時何分何秒ですか？
ii) 1900<=a<=2000,n=200のとき、今日は何時何分何秒ですか？

回答（C++プログラムコード）：

#include
#include
#include
#include

using namespace std;

// check if the year is a leap year
bool is_leap_year(int year)
{
	if (year%4==0 && year%100!=0 || year%400==0)
		return true;
	else
		return false;
}

// check if the day is valid
bool is_birthday_valid(int year, int month, int day)
{
	switch(month)
	{
	case 1:
		if (day>0 && day<32)
			return true;
		else
			return false;
		break;
	case 2:
		if (is_leap_year(year))
		{
			if (day>0 && day<30)
				return true;
			else
				return false;
		}
		else
		{
			if (day>0 && day<29)
				return true;
			else
				return false;
		}
		break;
	case 3:
		if (day>0 && day<32)
			return true;
		else
			return false;
		break;
	case 4:
		if (day>0 && day<31)
			return true;
		else
			return false;
		break;
	case 5:
		if (day>0 && day<32)
			return true;
		else
			return false;
		break;
	case 6:
		if (day>0 && day<31)
			return true;
		else
			return false;
		break;
	case 7:
		if (day>0 && day<32)
			return true;
		else
			return false;
		break;
	case 8:
		if (day>0 && day<32)
			return true;
		else
			return false;
		break;
	case 9:
		if (day>0 && day<31)
			return true;
		else
			return false;
		break;
	case 10:
		if (day>0 && day<32)
			return true;
		else
			return false;
		break;
	case 11:
		if (day>0 && day<31)
			return true;
		else
			return false;
		break;
	case 12:
		if (day>0 && day<32)
			return true;
		else
			return false;
		break;
	}
	return true;
}

// calculate days after the given day, not including the given day (return 0 when given 12/31)
int calculate_days_after(bool leap, int month, int day)
{
	int days=0;
	int days_of_month[]={31,28,31,30,31,30,31,31,30,31,30,31};
	if (leap)
	{
		days_of_month[1]=29;
	}
	if (month<12)
		for (int i=month;i<12;i++)
		{
			days+=days_of_month[i];
		}
	days+=(days_of_month[month-1]-day);
	return days;
}

// calculate days before the given day, including the given day (return 366 when given a leap year's 12/31)
int calculate_days_before(bool leap, int month, int day)
{
	int days=0;
	int days_of_month[]={31,28,31,30,31,30,31,31,30,31,30,31};
	if (leap)
	{
		days_of_month[1]=29;
	}
	for (int i=0;i1903)
			return (endyear-1904)/4+1;
		else
			return 0;
	}
	else if (is_leap_year(startyear))
	{
		return (endyear-startyear)/4+1;
	}
	else if (is_leap_year(startyear+1))
	{
		return (endyear-startyear-1)/4+1;
	}
	else if (is_leap_year(startyear+2))
	{
		return (endyear-startyear-2)/4+1;
	}
	else if (is_leap_year(startyear+3))
	{
		return (endyear-startyear-3)/4+1;
	}
	return 0;
}

// calculate the total days in n years
int calculate_total_days(int startyear, int n, int month, int day)
{
	return (n-1)*365+calculate_leap_year(startyear+1, startyear+n-1)+
		calculate_days_after(is_leap_year(startyear),month,day)+calculate_days_before(is_leap_year(startyear+n),month,day);
}

int calculate_current_days(int startyear, int startmonth, int startday, int year, int month, int day)
{
	return (year-startyear-1)*365+calculate_leap_year(startyear+1, year-1)+
		calculate_days_after(is_leap_year(startyear),startmonth,startday)+calculate_days_before(is_leap_year(year),month,day);
}

int main()
{
	// declaration
	struct tm *date;
	time_t now;
	int year, month, day; // current time
	int birthyear,birthmonth,birthday; // birthday
	float total_days; // total days of n years
	float current_days; // total days since birthday
	int current_seconds; // time in 24 hours
	int current_minutes;
	int current_hours;
	int n; // life span

	// get current time
	time(&now);
	date = localtime(&now);
	year = date->tm_year + 1900;
	month = date->tm_mon + 1;
	day = date->tm_mday;

	// input data
	int problemnum;
	cout<<"Please input problem number(1-2):"<>problemnum; // select problem number
	while(!(problemnum==1 || problemnum==2));
	if (problemnum==1)
	{
		n=80; // set life span
		cout<<"Please input the year you birth(1990-2000):"<>birthyear; // get birthyear
		while(birthyear<1990 || birthyear>2000);
	}
	else
	{
		n=200; // set life span
		cout<<"Please input the year you birth(1900-2000):"<>birthyear; // get birthyear
		while(birthyear<1900 || birthyear>2000);
	}
	cout<<"Please input the month you birth:"<>birthmonth; // get birthmonth
	while(birthmonth<1 || birthmonth>12);
	cout<<"Please input the day you birth:"<>birthday; // get birthday
	while(!is_birthday_valid(birthyear,birthmonth,birthday)); // check if the birthday is valid

	// calculate the result
	current_days=calculate_current_days(birthyear,birthmonth,birthday,year,month,day); // calculate total days since birthday
	total_days=calculate_total_days(birthyear,n,birthmonth,birthday); // calculate total days of n years since birthday
	current_seconds=(int)(current_days/total_days*3600*24); // calculate the time in 24 hours
	current_minutes=current_seconds/60;
	current_hours=current_minutes/60;
	current_seconds=current_seconds%60;
	current_minutes=current_minutes%60;

	// output the result
	cout<<"あなたの一生を24時間にたとえると今日は  "<
プログラムコード：LifeClock.cpp

URL: https://leybreeze.com/blog/wp-content/uploads/2012/02/LifeClock.cpp
回答できた問題の出力：

入力によって違います。
アルゴリズムの簡単な説明：

生年月日と現在の日付を取得

誕生日からn歳までの日数と誕生日から今までの日数を計算

24時間に変換

秒：誕生日から今までの日数/誕生日からn歳までの日数*3600*24

秒をよって分と時を計算
実行方法：LifeClock.exe　実行して小問の番号と生年月日を入力してください

URL: https://leybreeze.com/blog/wp-content/uploads/2012/02/LifeClock.exe
実行環境：Windows XP/Vista/7
ライセンス：GPLv3