我不明白为什么这段代码不起作用。我有几个月的天数，然后我从1900年到1900 + N + 1循环，以获得这些年的十三周五。然后我从几个月开始循环。我发现，无论是31天，28天还是30天的每一天，起始日都是星期一，下个月的开始日是星期一后的3天。所以我这样做了，我也发现每个第十三天之后只有13％在开始日后的7到1天所以我这样做了但我的代码仍然不起作用。每当我尝试打印它时，输出总是2,134,536或一些垃圾的数组值。有人可以帮我理解为什么它不对吗？
import java.io.BufferedReader;
import java.io.IOException;
import java.io.*;
import java.util.*;
public class friday {
public static void main(String[] args) throws IOException {
// the input file
BufferedReader f = new BufferedReader(new FileReader("friday.txt"));
// Use StringTokenizer vs. readLine/split -- lots faster
int N = Integer.parseInt(f.readLine());
int numdaysinmonth[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
int currentindexday = 0;
int numberofThirtday[] = {0, 0 ,0 ,0 ,0 ,0, 0};
//for loop from years
for (int x = 1900; x < x + N; x++) {
if(x%4 == 0 && x%100 != 0 || x%400==0 ){
numdaysinmonth[1] = 29;
}
else{
numdaysinmonth[1] = 28;
}
//the number of days to add to get from teh first starting day
int daystoadd = 0;
int startingday = 0;
for (int y = 0; y < numdaysinmonth.length; y++) {
if(numdaysinmonth[y] == 31){
daystoadd = 3;
}
else if(numdaysinmonth[y] == 30){
daystoadd = 2;
}
else if(numdaysinmonth[y] == 29){
daystoadd = 1;
}
else if(numdaysinmonth[y] == 28){
daystoadd = 0;
}
//each thirteenth day is the first day adding 5 to get the day 13%7 -1
currentindexday = startingday + 5;
if(currentindexday>6){
currentindexday = currentindexday%7;
}
numberofThirtday[currentindexday]++;
startingday += daystoadd;
}
}
for (int n = 0; n < numberofThirtday.length; n++) {
System.out.println(numberofThirtday[n]);
}
out.close();
System.exit(0);
}
}