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completed exam problem #5

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6 changes: 6 additions & 0 deletions .idea/vcs.xml
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43 changes: 41 additions & 2 deletions src/Main.java
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Original file line number Diff line number Diff line change
Expand Up @@ -3,10 +3,49 @@ public static void main(String[] args) {
System.out.println("Hello world!");

Deque<String> d1 = new ResizingArrayDeque<>();
// some test code here
d1.addFirst("Hello");
d1.addFirst("Bye");
System.out.println(d1.size());
System.out.println(d1.removeFirst());
System.out.println(d1.size());
System.out.println(d1.removeFirst());
System.out.println(d1.size());
d1.addFirst("Hello");
d1.addFirst("Bye");
d1.addLast("Hola");
d1.addLast("Adios");
System.out.println(d1.size());
System.out.println(d1.removeLast());
System.out.println(d1.size());
System.out.println(d1.removeLast());
System.out.println(d1.size());
System.out.println(d1.removeLast());
System.out.println(d1.size());
System.out.println(d1.removeLast());
System.out.println(d1.size());


Deque<String> d2 = new SinglyLinkedDeque<>();
// some test code here
d2.addFirst("Hello");
d2.addFirst("Bye");
System.out.println(d2.size());
System.out.println(d2.removeFirst());
System.out.println(d2.size());
System.out.println(d2.removeFirst());
System.out.println(d2.size());
d2.addFirst("Hello");
d2.addFirst("Bye");
d2.addLast("Hola");
d2.addLast("Adios");
System.out.println(d2.size());
System.out.println(d2.removeLast());
System.out.println(d2.size());
System.out.println(d2.removeLast());
System.out.println(d2.size());
System.out.println(d2.removeLast());
System.out.println(d2.size());
System.out.println(d2.removeLast());
System.out.println(d2.size());

}
}
67 changes: 47 additions & 20 deletions src/ResizingArrayDeque.java
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,18 @@ public int size() {
@Override
public void addFirst(ItemType item) {
// consider the case of adding to an empty list
if(size == 0){
data[0] = item;
} else {
checkSize();
//move everything over
for (int i = size + 1; i > 0 ; i--) {
data[i] = data[i-1];
}
data[0] = item;
}
//update size
size++;
// consider the case of adding to a non-empty list

// There is a private helper method checkSize() defined below to check/resize
Expand All @@ -47,6 +59,13 @@ public void addFirst(ItemType item) {
public void addLast(ItemType item) {
// consider the case of adding to an empty list
// consider the case of adding to a non-empty list
if (size == 0){
addFirst(item);
} else {
checkSize();
data[size()] = item;
size ++;
}

// There is a private helper method checkSize() defined below to check/resize
// that you can call as needed to check if the array is full and resize it.
Expand All @@ -61,16 +80,21 @@ public void addLast(ItemType item) {
public ItemType removeFirst() {
// check if empty
// if empty: do nothing and return null

// if there's only one item: is this a special case?

// if not empty:
// 0. figure out a way to access the item in the front
// 1. make a variable to save a copy of the item at the front
// 2. remove the item at the front
// 3. return the variable that has the saved copy of the item at the front

return null;
if (size == 0){
return null;
} else if (size == 1){
ItemType tempVar = data[0];
data[0] = null;
size = 0;
return tempVar;
} else {
ItemType tempVar = data[0];
for (int i = 0; i < size() - 1 ; i++) {
data[i] = data [i +1];
}
size --;
return tempVar;
}
}

/**
Expand All @@ -82,16 +106,19 @@ public ItemType removeFirst() {
public ItemType removeLast() {
// check if empty
// if empty: do nothing and return null

// if there is only one item: is this a special case?

// if not empty, has more than one item:
// 0. figure out a way to access the item in the back
// 1. make a variable to save a copy of the item at the back
// 2. remove the item at the back
// 3. return the variable that has the saved copy of the item at the back

return null;
if( size == 0 ){
return null;
} else if ( size == 1 ){
ItemType tempVar = data[0];
data[0] = null;
size = 0;
return tempVar;
} else {
ItemType tempVar = data[size() - 1];
data[size()-1] = null;
size --;
return tempVar;
}
}

// helper method to check to see if the size has reached the capacity
Expand Down
75 changes: 55 additions & 20 deletions src/SinglyLinkedDeque.java
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,17 @@ public int size() {
@Override
public void addFirst(ItemType item) {
// consider the case of adding to an empty list
if (size == 0 ){
head = new Node();
head.data = item;
head.next = null;
} else {
Node theNewOne = new Node();
theNewOne.data = item;
theNewOne.next = head;
head = theNewOne;
}
size ++;
// consider the case of adding to a non-empty list
}

Expand All @@ -46,6 +57,20 @@ public void addFirst(ItemType item) {
@Override
public void addLast(ItemType item) {
// consider the case of adding to an empty list
if (size == 0 ){
head.data = item;
head.next = null;
} else {
Node currentNode = head;
while (currentNode.next != null ){
currentNode = currentNode.next;
}
Node theNewOne = new Node();
theNewOne.data = item;
theNewOne.next = null;
currentNode.next = theNewOne;
}
size++;
// consider the case of adding to a non-empty list
}

Expand All @@ -57,17 +82,20 @@ public void addLast(ItemType item) {
@Override
public ItemType removeFirst() {
// check if empty
// if empty: do nothing and return null
if (size == 0){
return null;
} else if ( size == 1 ){
ItemType temp = head.data;
head = null;
size --;
return temp;
} else {
ItemType temp = head.data;
head = head.next;
size --;
return temp;
}

// if there's only one item: is this a special case?

// if not empty:
// 0. figure out a way to access the item in the front
// 1. make a variable to save a copy of the item at the front
// 2. remove the item at the front
// 3. return the variable that has the saved copy of the item at the front

return null;
}

/**
Expand All @@ -78,16 +106,23 @@ public ItemType removeFirst() {
@Override
public ItemType removeLast() {
// check if empty
// if empty: do nothing and return null

// if there is only one item: is this a special case?

// if not empty, has more than one item:
// 0. figure out a way to access the item in the back
// 1. make a variable to save a copy of the item at the back
// 2. remove the item at the back
// 3. return the variable that has the saved copy of the item at the back
if (size == 0 ){
return null;
} else if ( size == 1 ){
ItemType temp = head.data;
head = null;
size --;
return temp;
} else {
Node currentNode = head;
while (currentNode.next != null ){
currentNode = currentNode.next;
}
ItemType temp = currentNode.data;
currentNode = null;
size --;
return temp;
}

return null;
}
}