题目

解题代码

class Solution {
    static String[] ss = new String[]{"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};
    static int[] nums = new int[]{31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
    public String dayOfTheWeek(int day, int month, int year) {
        //1970 的最后一天（星期四）
        int ans = 4;
        for(int i = 1971; i < year; i++ ) {
            boolean isLeap = (i % 4 == 0 && i % 100 != 0 ) || i % 400 == 0;
            ans += isLeap ? 366 : 365;
        }
        for(int i = 1; i < month; i++ ) {
            ans += nums[i - 1];
            if(i == 2 && ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0)) {
                ans++;
            }
        }
        ans += day;
        return ss[ans % 7];
    }
}

import java.util.Calendar;
import java.util.Date;
class Solution {
    public String dayOfTheWeek(int day, int month, int year) {
        String [] weeks = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};
        Calendar cal = Calendar.getInstance();
        cal.setTime(new Date(year-1900,month - 1, day));
        int w = cal.get(Calendar.DAY_OF_WEEK) - 1;
        if(w < 0 ) w= 0;
        return weeks[w];
    }
}