week 2

week2/Makefile

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+list: list.c list.h
+	gcc -o list list.c list.h

week2/list.c

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+/*
+ * Author: Walter
+ * Student ID: 1930006025
+ * Week_2
+ */
+
+#include "list.h"
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+// Write all your functions here.
+bool IsEmpty(Node *head) {
+	if (head == NULL) {
+		return true;
+	} else {
+		return false;
+	}
+}
+
+/* code from pdf */
+Node *InsertNode(Node **phead, int index, double x) {
+	if (index < 0)
+		return NULL;
+	int currIndex = 1;
+	Node *currNode = *phead;
+	while (currNode != NULL && index > currIndex) {
+		currNode = currNode->next;
+		currIndex++;
+	}
+	if (index > 0 && currNode == NULL)
+		return NULL;
+	Node *newNode = (Node *)malloc(sizeof(Node));
+	newNode->data = x;
+	if (index == 0) {
+		newNode->next = *phead;
+		*phead = newNode;
+	} else {
+		newNode->next = currNode->next;
+		currNode->next = newNode;
+	}
+	return newNode;
+}
+
+int FindNode(Node *head, double x) {
+	int position;
+	Node *pnode;
+
+	/* position start from 1 */
+	for (pnode = head, position = 1; pnode; pnode = pnode->next, position++) {
+		if (pnode->data == x) {
+			return position;
+		}
+	}
+
+	return 0;
+}
+
+int DeleteNode(Node **phead, double x) {
+	/* position start from 1 */
+	int position;
+	Node *pnode;
+	Node *delNode;
+
+	/* if delete the first node */
+	if ((*phead)->data == x) {
+		delNode = *phead;
+		*phead = (*phead)->next;
+		free(delNode);
+		return 1;
+	}
+
+	/* if not the first node */
+	for (pnode=*phead, position=2; pnode->next; pnode=pnode->next, position++) {
+		/* loop for pnode->next->data == x */
+		if (pnode->next->data == x) {
+			/* delete node */
+			delNode = pnode->next;
+			pnode->next = pnode->next->next;
+			free(delNode);
+			return position;
+		}
+	}
+	
+	/* if node not found, return 0 */
+	return 0;
+}
+
+void DisplayList(Node *head) {
+	Node *pnode;
+	/* loop for each node */
+	for (pnode=head; pnode; pnode=pnode->next) {
+		printf("%f ", pnode->data);
+	}
+	/* new line at the end */
+	printf("\n");
+}
+
+void DestroyList(Node *head) {
+	Node *pnode = head;
+	Node *delNode;
+	/* loop for each node */
+	while (pnode) {
+		/* store the tmp node */
+		delNode = pnode;
+		pnode = pnode->next;
+		free(delNode);
+	}
+}
+
+// Testing all the functions:
+int main(void) {
+	Node *head = NULL;
+
+	// Output: true
+	printf("%s\n", IsEmpty(head) ? "true" : "false");
+
+	// Must output an empty line:
+	DisplayList(head);
+
+	// Must output "insert failed":
+	Node *result = InsertNode(&head, 20, 7);
+	printf("%s\n", result == NULL ? "insert failed" : "insert succeeded");
+
+	// Output: 0.000000 1.000000 2.000000 3.000000 4.000000
+	for (int i = 0; i < 5; i++) {
+		InsertNode(&head, i, i);
+	}
+	DisplayList(head);
+
+	// Output: false
+	printf("%s\n", IsEmpty(head) ? "true" : "false");
+
+	// Output: 4.000000 3.000000 2.000000 1.000000 0.000000
+	// 0.000000 1.000000 2.000000 3.000000 4.000000
+	for (int i = 0; i < 5; i++) {
+		InsertNode(&head, 0, i);
+	}
+	DisplayList(head);
+
+	// Output: 0.000000 is at position 5
+	//         2.000000 is at position 3
+	//         4.000000 is at position 1
+	//         6.000000 is not in the list
+	for (int i = 0; i < 7; i += 2) {
+		int idx = FindNode(head, i);
+		if (idx > 0) {
+			printf("%f is at position %d\n", (double)i, idx);
+		} else {
+			printf("%f is not in the list\n", (double)i);
+		}
+	}
+
+	// Output: inserted 10.000000
+	//         4.000000 3.000000 2.000000 10.000000 1.000000 0.000000
+	//         0.000000 1.000000 2.000000 3.000000 4.000000
+	Node *in = InsertNode(&head, 3, 10);
+	printf("inserted %f\n", in->data);
+	DisplayList(head);
+
+	// Output: 4.000000 3.000000 2.000000 10.000000 1.000000
+	// 0.000000 1.000000 2.000000 3.000000 4.000000
+	//         3.000000 2.000000 10.000000 1.000000
+	//         0.000000 1.000000 2.000000 3.000000 4.000000
+	//         3.000000 2.000000 10.000000 1.000000
+	//         0.000000 1.000000 2.000000 3.000000
+	DeleteNode(&head, 0); // Delete in the middle of the list.
+	DisplayList(head);
+	DeleteNode(&head, 4); // Delete at the front of the list.
+	DisplayList(head);
+	DeleteNode(&head, 4); // Delete at the end of the list.
+	DisplayList(head);
+
+	DestroyList(head);
+	head = NULL;
+
+	return 0;
+}

week2/list.h

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+#include <stdbool.h>
+
+typedef struct node {
+	double data;
+	struct node *next;
+} Node;
+
+/* function: tests whether a list is empty
+input: head: pointer to the first node
+output: true if the list is empty and false otherwise
+*/
+bool IsEmpty(Node *head);
+
+/* function: inserts a new node with certain data after a certain position
+input: phead: pointer to the pointer to the first node
+index: the new node is inserted after position index
+insert a new node as the head if index is 0
+x: data of the new node
+output: a pointer to the new node if insertion is successful, NULL otherwise
+*/
+Node *InsertNode(Node **phead, int index, double x);
+
+/* function: finds node with certain data
+input: head: pointer to the first node
+x: the first node whose data = x is returned
+output: returns the position of the first node whose data = x
+returns 0 if no such node exists
+*/
+int FindNode(Node *head, double x);
+
+/* function: deletes a node with certain data
+input: phead: pointer to the pointer to the first node
+x: the first node whose data = x is deleted
+output: returns the position of the deleted node
+returns 0 if no such node exists
+*/
+int DeleteNode(Node **phead, double x);
+
+/* function: prints all the nodes in the list
+input: head: pointer to the first node
+*/
+void DisplayList(Node *head);
+
+/* function: deletes all the nodes in the list and frees their memory
+input: head: pointer to the first node
+*/
+void DestroyList(Node *head);