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Java Exercises: Test whether two lines PQ and RS are parallel

Java Basic: Exercise-222 with Solution

Write a Java program to test whether two lines PQ and RS are parallel. The four points are P(x1, y1), Q(x2, y2), R(x3, y3), S(x4, y4).

Input:
−100 ≤ x1, y1, x2, y2, x3, y3, x4, y4 ≤ 100
Each value is a real number with at most 5 digits after the decimal point.

Sample Solution:

Java Code:

 import java.util.*;
 
class Main {
     
    public static void main(String args[]){
        Scanner in = new Scanner(System.in);
		System.out.println("Input P(x1,y1),separated by a space.");
        double x1 = in.nextDouble(), y1 = in.nextDouble();
		System.out.println("Input Q(x2,y2),separated by a space.");
        double x2 = in.nextDouble(), y2 = in.nextDouble();
		System.out.println("Input R(x3,y3),separated by a space.");
        double x3 = in.nextDouble(), y3 = in.nextDouble();
		System.out.println("Input S(x4,y4),separated by a space.");
        double x4 = in.nextDouble(), y4 = in.nextDouble();
        double p1 = x2 - x1, p2 = y2 - y1, q1 = x4 - x3, q2 = y4 - y3,
        r1 = x3 - x1, r2 = y3 - y1, s1 = x4 - x1, s2 = y4 - y1;
        if(Math.abs(p1*q2 - p2*q1)<1e-9)
           System.out.println("Two lines are parallel.");
        else
           System.out.println("Two lines are not parallel.");
     }
 }

Sample Output: 

Input P(x1,y1),separated by a space.
 5 6
Input Q(x2,y2),separated by a space.
 4 2
Input R(x3,y3),separated by a space.
 5 3
Input S(x4,y4),separated by a space.
 5 6
Two lines are not parallel.

Flowchart:

Flowchart: Java exercises: Accepts six numbers as input and sorts them in descending order.

Java Code Editor:

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Previous: Write a Java program that accepts six numbers as input and sorts them in descending order.
Next: >Write a Java program to find the maximum sum of a contiguous subsequence from a given sequence of numbers a1, a2, a3, ... an. A subsequence of one element is also a continuous subsequence.

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Java: Tips of the Day

Java: Anagrams

Generates all anagrams of a string.

public static List<String> anagrams(String input) {
    if (input.length() <= 2) {
        return input.length() == 2
                ? Arrays.asList(input, input.substring(1) + input.substring(0, 1))
                : Collections.singletonList(input);
    }
    return IntStream.range(0, input.length())
            .mapToObj(i -> new SimpleEntry<>(i, input.substring(i, i + 1)))
            .flatMap(entry ->
                    anagrams(input.substring(0, entry.getKey()) + input.substring(entry.getKey() + 1))
                            .stream()
                            .map(s -> entry.getValue() + s))
            .collect(Collectors.toList());
}

Ref: https://bit.ly/3rvAdAK