算法笔记_154:算法提高 日期计算(Java)

目录

1 问题描述

2 解决方案

 

---

1 问题描述

问题描述

　　已知2011年11月11日是星期五，问YYYY年MM月DD日是星期几？注意考虑闰年的情况。尤其是逢百年不闰，逢400年闰的情况。

输入格式

　　输入只有一行
　　YYYY MM DD

输出格式

　　输出只有一行
　　W

数据规模和约定

　　1599 <= YYYY <= 2999
　　1 <= MM <= 12
　　1 <= DD <= 31，且确保测试样例中YYYY年MM月DD日是一个合理日期
　　1 <= W <= 7，分别代表周一到周日

样例输入

2011 11 11

样例输出

5

---

2 解决方案

具体代码如下：

import java.util.Scanner;

public class Main {

    public boolean judgeYear(int year) {
        if(year % 400 == 0 || (year % 4 == 0 && year % 100 != 0))
            return true;  //此时为闰年
        return false;   //此时为平年
    }

    public int getMonth(int year, int month) {  //获取月份天数
        if(month == 1 || month == 3 || month == 5 || month == 7 ||
                month == 8 || month == 10 || month == 12)
            return 31;
        if(month == 4 || month == 6 || month == 9 || month == 11)
            return 30;
        if(judgeYear(year) && month == 2)
            return 29;
        if(!judgeYear(year) && month == 2)
            return 28;
        return 0;
    }

    public void getResult(String date) {
        String[] temp = date.split(" ");
        int year = Integer.valueOf(temp[0]);
        int month = Integer.valueOf(temp[1]);
        int day = Integer.valueOf(temp[2]);
        int countDay = 0;
        int result = 0;  //最终结果
        if(year > 2011) {
            for(int i = 1;i < month;i++)
                countDay += getMonth(year, i);
            countDay += day;
            for(int i = year - 1;i > 2011;i--) {  //跳出循环时i = 2011
                if(judgeYear(i))
                    countDay += 366;
                else
                    countDay += 365;
            }
            countDay = countDay + 19 + 31;  //加上2011年11月份剩余天数和12月份31天
            result = 5 + countDay % 7;
            if(result != 7)
                result = result % 7;
        } else if(year < 2011){
            countDay = countDay + (getMonth(year, month) - day);
            month++;
            for(;month <= 12;month++)
                countDay += getMonth(year, month);
            for(int i = year + 1;i < 2011;i++) {  //跳出循环时i = 2011
                if(judgeYear(i))
                    countDay += 366;
                else
                    countDay += 365;
            }
            for(int i = 1;i <= 10;i++)
                countDay += getMonth(2011, i);
            countDay += 11;
            result = 5 - countDay % 7;
            if(result == 0)
                result = 7;
            else if(result == -1)
                result = 6;
            else if(result == -2)
                result = 5;
        } else if(year == 2011) {
            if(month > 11) {
                countDay = countDay + 19 + day;
            } else if(month == 11) {
                if(day >= 11) {
                    countDay = day - 11;
                } else if(day < 11)
                    countDay = 11 - day;
            } else if(month < 11) {
                countDay += getMonth(2011, month) - day;
                int i = month + 1;
                for(;i <= 10;i++)
                    countDay += getMonth(2011,i);
                countDay += 11;
            }
            if(month >= 11 && day >= 11) {
                result = 5 + countDay % 7;
                if(result != 7)
                    result = result % 7;
            } else {
                result = 5 - countDay % 7;
                if(result == 0)
                    result = 7;
                else if(result == -1)
                    result = 6;
                else if(result == -2)
                    result = 5;
            }
        }
        System.out.println(result);
    }

    public static void main(String[] args) {
        Main test = new Main();
        Scanner in = new Scanner(System.in);
        String date = in.nextLine();
        test.getResult(date);
    }
}