Java Problem Statements.

Differencebetweentwodates.java

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+//MIT License: https://bit.ly/35gZLa3
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.time.Period;
+import java.time.ZoneId;
+import java.time.ZonedDateTime;
+import java.time.temporal.ChronoUnit;
+import java.util.Calendar;
+import java.util.concurrent.TimeUnit;
+
+public class Main {
+
+    public static void main(String[] args) {
+
+        System.out.println("\nBefore JDK 8:");
+
+        Calendar cal1 = Calendar.getInstance();
+        cal1.set(2019, 0, 1);
+        Calendar cal2 = Calendar.getInstance();
+        cal2.set(2020, 2, 1);
+
+        System.out.println("\nDate/Calendar case: " + cal1.getTime() + " <-> " + cal2.getTime());
+
+        long inMs = Math.abs(cal1.getTimeInMillis() - cal2.getTimeInMillis());
+        long inDays = Math.abs(TimeUnit.DAYS.convert(inMs, TimeUnit.MILLISECONDS));
+
+        System.out.println("Difference in milliseconds is: " + inMs);
+        System.out.println("Difference in days is: " + inDays);
+
+        System.out.println("\nStarting with JDK 8:");
+
+        LocalDate ld1 = LocalDate.of(2019, 1, 1);
+        LocalDate ld2 = LocalDate.of(2020, 3, 1);
+
+        System.out.println("\nLocalDate case: " + ld1 + " <-> " + ld2);
+
+        long between_In_Days = Math.abs(ChronoUnit.DAYS.between(ld1, ld2));
+        long between_In_Months = Math.abs(ChronoUnit.MONTHS.between(ld1, ld2));
+        long between_In_Years = Math.abs(ChronoUnit.YEARS.between(ld1, ld2));
+        long until_In_Days = Math.abs(ld1.until(ld2, ChronoUnit.DAYS));
+        long until_In_Months = Math.abs(ld1.until(ld2, ChronoUnit.MONTHS));
+        long until_In_Years = Math.abs(ld1.until(ld2, ChronoUnit.YEARS));
+        Period period = ld1.until(ld2);
+        System.out.println("Difference as Period: "
+                + period.getYears() + "y" + period.getMonths() + "m" + period.getDays() + "d");
+        System.out.println("Difference in days is via between(): " + between_In_Days);
+        System.out.println("Difference in months is via between(): " + between_In_Months);
+        System.out.println("Difference in years is via between(): " + between_In_Years);
+        System.out.println("Difference in days is via until(): " + until_In_Days);
+        System.out.println("Difference in months is via until(): " + until_In_Months);
+        System.out.println("Difference in years is via until(): " + until_In_Years);
+
+        LocalDateTime ldt1 = LocalDateTime.of(2019, 1, 1, 22, 15, 15);
+        LocalDateTime ldt2 = LocalDateTime.of(2020, 1, 1, 23, 15, 15);
+
+        System.out.println("\nLocalDateTime case: " + ldt1 + " <-> " + ldt2);
+
+        long betweenInMinutesWithoutZone = Math.abs(ChronoUnit.MINUTES.between(ldt1, ldt2));
+        long untilInMinutesWithoutZone = Math.abs(ldt1.until(ldt2, ChronoUnit.HOURS));
+        System.out.println("Difference in minutes without zone: " + betweenInMinutesWithoutZone);
+        System.out.println("Difference in hours without zone: " + untilInMinutesWithoutZone);
+
+        System.out.println("\nZonedDateTime case:");
+
+        ZonedDateTime zdt1 = ldt1.atZone(ZoneId.of("Europe/Bucharest"));
+        ZonedDateTime zdt2 = zdt1.withZoneSameInstant(ZoneId.of("Australia/Perth")).plusHours(1);
+        ZonedDateTime zdt3 = ldt2.atZone(ZoneId.of("Australia/Perth"));
+
+        long betweenInMinutesWithZone12 = Math.abs(ChronoUnit.MINUTES.between(zdt1, zdt2));
+        long untilInHoursWithZone12 = Math.abs(zdt1.until(zdt2, ChronoUnit.HOURS));
+        long betweenInMinutesWithZone13 = Math.abs(ChronoUnit.MINUTES.between(zdt1, zdt3));
+        long untilInHoursWithZone13 = Math.abs(zdt1.until(zdt3, ChronoUnit.HOURS));
+
+        System.out.println("Europe/Bucharest: " + zdt1 + " <-> Australia/Perth: " + zdt2);
+        System.out.println("Difference in minutes with zone (same instant): " + betweenInMinutesWithZone12);
+        System.out.println("Difference in hours with zone (same instant): " + untilInHoursWithZone12);
+
+        System.out.println("\nEurope/Bucharest: " + zdt1 + " <-> Australia/Perth: " + zdt3);
+        System.out.println("Difference in minutes with zone (not same instant): " + betweenInMinutesWithZone13);
+        System.out.println("Difference in hours with zone: " + untilInHoursWithZone13);
+    }
+} 

publicclassBogoSort.java

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+public class BogoSort 
+{
+	public static void main(String[] args)
+	{
+		//Enter array to be sorted here
+		int[] arr={4,5,6,0,7,8,9,1,2,3};
+
+		BogoSort now=new BogoSort();
+		System.out.print("Unsorted: ");
+		now.display1D(arr);
+
+		now.bogo(arr);
+
+		System.out.print("Sorted: ");
+		now.display1D(arr);
+	}
+	void bogo(int[] arr)
+	{
+		//Keep a track of the number of shuffles
+		int shuffle=1;
+		for(;!isSorted(arr);shuffle++)
+			shuffle(arr);
+		//Boast
+		System.out.println("This took "+shuffle+" shuffles.");
+	}
+	void shuffle(int[] arr)
+	{
+		//Standard Fisher-Yates shuffle algorithm
+		int i=arr.length-1;
+		while(i>0)
+			swap(arr,i--,(int)(Math.random()*i));
+	}
+	void swap(int[] arr,int i,int j)
+	{
+		int temp=arr[i];
+		arr[i]=arr[j];
+		arr[j]=temp;
+	}
+	boolean isSorted(int[] arr)
+	{
+
+		for(int i=1;i<arr.length;i++)
+			if(arr[i]<arr[i-1])
+				return false;
+		return true;
+	}
+	void display1D(int[] arr)
+	{
+		for(int i=0;i<arr.length;i++)
+			System.out.print(arr[i]+" ");
+		System.out.println();
+	} 
+}
+