Question

Question 1

A substring of String s is a sequence of k >= 0 characters in s, in the order in which they occur in s.

The letters in a substring may be either contiguous (next to each other) or non-contiguous in the original String s.

For instance, these are the substrings of String s="abc".

String s All substrings of s

======== ==================================

"abc" "" "a" "b" "ab" "c" "ac" "bc" "abc"

Write a function allSubstrings that returns an ArrayList containing all the substrings (contiguous or non-contiguous) of a String parameter s, and test it on the String "abcde".

// Return all substrings of the String s

public static ArrayList allSubstrings(String s) { ... }

Question 2

Implement a function that reads numbers in from a file with one number per line and outputs all the possible sums that can be formed by subsets of the numbers. For instance, if the numbers in the file are 1 2 4, then the output would be 0, 1, 2, 4, 3, 5, 6, 7. Note that 0 is in the output because it uses none of the numbers, while 7 is the sum of all of the numbers.

// Return all sums that can be formed from subsets of elements in arr

public static ArrayList allSums( ArrayList arr ) { ... }

q1.java

package a1;

/**

* Name:

* Student ID:

* Description of solution:

*/

import static org.junit.Assert.*;

public class Q3 {

// Return the number of ways to choose a subset of k distinct elements from a

set of n elements

public static int C( int n, int k ) {

return 0;

}

public static void main(String[] args) {

System.out.println("Testing...");

assertEquals(C(14,3), 364);

assertEquals(C(14,11), 364);

assertEquals(C(18,8), 43758);

System.out.println("Success!");

}

}

q2.java

package a1;

/**

* Name:

* Student ID:

* Description of solution:

*/

import java.io.BufferedReader;

import java.io.FileReader;

import java.util.ArrayList;

import static org.junit.Assert.*;

public class Q2 {

// Return all sums that can be formed from subsets of elements in arr

public static ArrayList allSums( ArrayList arr ) {

return null;

}

public static void main(String[] args) {

//https://www.baeldung.com/java-file-to-arraylist

ArrayList result = new ArrayList();//=

Files.readAllLines(Paths.get("nums.txt"));

try {

BufferedReader br = new BufferedReader(new

FileReader("nums.txt"));

while (br.ready()) {

result.add(Integer.getInteger(br.readLine()));

}

} catch (Exception e) {

System.out.println(e.getMessage());

}

ArrayList sums = allSums(result);

System.out.println("Testing...");

assertEquals(sums.size(), 8);

assertEquals(sums.contains(0), true);

assertEquals(sums.contains(1), true);

assertEquals(sums.contains(2), true);

assertEquals(sums.contains(4), true);

assertEquals(sums.contains(3), true);

assertEquals(sums.contains(5), true);

assertEquals(sums.contains(6), true);

assertEquals(sums.contains(7), true);

System.out.println("Success!");

}

}

q3.java

package a1;

/**

* Name:

* Student ID:

* Description of solution:

*/

import java.util.ArrayList;

import static org.junit.Assert.*;

public class Q1 {

// Return all substrings of the String s

public static ArrayList allSubstrings(String s){

return null;

}

public static void main(String[] args) {

ArrayList s = allSubstrings("abcde");

System.out.println("Testing...");

assertEquals(s.size(), 32);

assertEquals(s.contains(""), true);

assertEquals(s.contains("abcd"), true);

assertEquals(s.contains("abce"), true);

assertEquals(s.contains("abcde"), true);

System.out.println("Success!");

}

}

nums.txt

1

2

4

Answer 1

package a1;

/**

* Name:

* Student ID:

* Description of solution:

*/

import java.util.ArrayList;

import static org.junit.Assert.*;

public class Q1 {

// Return all substrings of the String s

public static ArrayList<String> allSubstrings(String s) {
        ArrayList<String> result = new ArrayList<>();
        if(s.isEmpty()) {
                result.add("");
                return result;
        }
        
        ArrayList<String> subResult = allSubstrings(s.substring(0, s.length() - 1));
        char c = s.charAt(s.length() - 1);
        
        result.addAll(subResult);
        for(String x: subResult) {
                result.add(x + c);
        }
        
        return result;
}

public static void main(String[] args) {

        ArrayList s = allSubstrings("abcde");

        System.out.println("Testing...");

        assertEquals(s.size(), 32);

        assertEquals(s.contains(""), true);

        assertEquals(s.contains("abcd"), true);

        assertEquals(s.contains("abce"), true);

        assertEquals(s.contains("abcde"), true);

        System.out.println("Success!");

}

}





Answering your first question, Since both are different question and require significant efforts on both.. Please ask them separately. 

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