Question

instructions: Write a non-member method named bagScaler, which removes from a Bag all elements that occur less than N times . The method returns the number of copies removed.
For example, if B = {Bob, Joe, Bob, Ned, Bob, Ned, Kim}, then calling bagScaler(B, 3) removes Joe, Ned, and Kim making B = {Bob, Bob, Bob}, and returns 4 because it removed 2 copies of Ned, one of Joe, and one of Kim.
Note: There's no iterator, but there is a toArray method.

public class BagWrapper {

public static interface Bag {
public int size();
public boolean isEmpty();
public void add(Object e);
public boolean isMember(Object e);
public boolean remove(Object e);
public int removeAll(Object e);
public int count(Object e);
public void clear();
public Object[] toArray();
}

public static class DynamicBag implements Bag{

private Object[] elements;
private int currentSize;
private static final int DEFAULT_SIZE = 10;

public DynamicBag(int initialSize) {
if (initialSize < 1) {
throw new IllegalArgumentException("Size must be at least 1");
}
this.elements = new Object[initialSize];
this.currentSize = 0;
}

public DynamicBag() {
this(DEFAULT_SIZE);
}

@Override
public int size() {
return this.currentSize;
}

@Override
public boolean isEmpty() {
return this.size() == 0;
}

@Override
public void add(Object e) {
if (e == null) {
throw new IllegalArgumentException("Argument cannot be null");
}
if (this.size() == this.elements.length) {
this.reAllocate();
}
this.elements[this.currentSize++] = e;
}

private void reAllocate() {
Object temp[] = new Object[2*this.size()];
for (int i=0; i < this.size(); ++i) {
temp[i] = this.elements[i];
}
this.elements = temp;
}

@Override
public boolean isMember(Object e) {
return this.count(e) > 0;
}

@Override
public boolean remove(Object e) {
for (int i=0; i < this.size(); ++i) {
if (this.elements[i].equals(e)) {
this.elements[i] = this.elements[this.currentSize-1];
this.elements[this.currentSize-1] = null;
--this.currentSize;
return true;
}
}
return false;
}

@Override
public int removeAll(Object e) {
int result = 0;
while(this.remove(e)) {
result++;
}
return result;
}

@Override
public int count(Object e) {
int result = 0;
for (int i=0; i < this.size(); ++i) {
if (this.elements[i].equals(e)) {
result++;
}
}
return result;
}

@Override
public void clear() {
for (int i=0; i < this.size(); ++i) {
this.elements[i] = null;
}
this.currentSize = 0;
}

public Object[] toArray() {
Object[] result = new Object[this.size()];
for (int i=0; i < this.size(); ++i) {
result[i] = this.elements[i];
}
return result;
}

}

// NON-MEMBER METHOD

public static int bagScaler(Bag B, int n) {

// ADD YOUR CODE HERE


return n; //dummy return
}
}

Answer 1

119 A1200 <terminated> BagWrapper 121 public Object[] toArray() { Object[] result = new Object[this.size()]; for (int i = 0; i < this.size(); ++i) { result[i] = this.elements[i]; 122 [Bob, Bob, Bob] 123 124 125 return result; 126 127 128 129 130 // NON-MEMBER METHOD public static int bagScaler (Bag B, int n) { 1310 132 133 int r = 0; Object[] data = B.toArray(); for(Object d: data) { if(B.count(d) < n) { while(B.count(d) != 0) { B.remove(d); r++; 144 145 146 return r; 147 1480 149 150 151 152 153 public static void main(String args[]) { Bag x = new DynamicBag(); x.add("Bob"); x.add("Joe"); x.add("Bob"); x.add("Ned"); x.add("Bob"); x.add("Ned"); x.add("Kim"); 154 155 156 157 158 159 160 161 } System.out.println(bagScaler(x, 3)); System.out.println(Arrays.toString(x.toArray()));

package apr26;

import java.util.Arrays;

public class BagWrapper {

    public static interface Bag {
        public int size();

        public boolean isEmpty();

        public void add(Object e);

        public boolean isMember(Object e);

        public boolean remove(Object e);

        public int removeAll(Object e);

        public int count(Object e);

        public void clear();

        public Object[] toArray();
    }

    public static class DynamicBag implements Bag {

        private Object[] elements;
        private int currentSize;
        private static final int DEFAULT_SIZE = 10;

        public DynamicBag(int initialSize) {
            if (initialSize < 1) {
                throw new IllegalArgumentException("Size must be at least 1");
            }
            this.elements = new Object[initialSize];
            this.currentSize = 0;
        }

        public DynamicBag() {
            this(DEFAULT_SIZE);
        }

        @Override
        public int size() {
            return this.currentSize;
        }

        @Override
        public boolean isEmpty() {
            return this.size() == 0;
        }

        @Override
        public void add(Object e) {
            if (e == null) {
                throw new IllegalArgumentException("Argument cannot be null");
            }
            if (this.size() == this.elements.length) {
                this.reAllocate();
            }
            this.elements[this.currentSize++] = e;
        }

        private void reAllocate() {
            Object temp[] = new Object[2 * this.size()];
            for (int i = 0; i < this.size(); ++i) {
                temp[i] = this.elements[i];
            }
            this.elements = temp;
        }

        @Override
        public boolean isMember(Object e) {
            return this.count(e) > 0;
        }

        @Override
        public boolean remove(Object e) {
            for (int i = 0; i < this.size(); ++i) {
                if (this.elements[i].equals(e)) {
                    this.elements[i] = this.elements[this.currentSize - 1];
                    this.elements[this.currentSize - 1] = null;
                    --this.currentSize;
                    return true;
                }
            }
            return false;
        }

        @Override
        public int removeAll(Object e) {
            int result = 0;
            while (this.remove(e)) {
                result++;
            }
            return result;
        }

        @Override
        public int count(Object e) {
            int result = 0;
            for (int i = 0; i < this.size(); ++i) {
                if (this.elements[i].equals(e)) {
                    result++;
                }
            }
            return result;
        }

        @Override
        public void clear() {
            for (int i = 0; i < this.size(); ++i) {
                this.elements[i] = null;
            }
            this.currentSize = 0;
        }

        public Object[] toArray() {
            Object[] result = new Object[this.size()];
            for (int i = 0; i < this.size(); ++i) {
                result[i] = this.elements[i];
            }
            return result;
        }

    }

    // NON-MEMBER METHOD
    public static int bagScaler(Bag B, int n) {
        
        int r = 0;
        
        Object[] data = B.toArray();
        for(Object d: data) {
            if(B.count(d) < n) {                    
                while(B.count(d) != 0) {
                    B.remove(d);
                    r++;
                }                    
            }
        }

        return r;
    }
    
    public static void main(String args[]) {
        Bag x = new DynamicBag();
        x.add("Bob");
        x.add("Joe");
        x.add("Bob");
        x.add("Ned");
        x.add("Bob");
        x.add("Ned");
        x.add("Kim");
        
        System.out.println(bagScaler(x, 3));
        System.out.println(Arrays.toString(x.toArray()));
    }
}

**************************************************
I have provided a test code in main method.. You may or may not consume that.

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