assignment 1 problem 1

assignment1/problem1/list.c

@@ -0,0 +1,195 @@
+/*
+ * Author: Walter
+ * Student ID: 1930006025
+ * Assignment_1_problem_1
+ */
+
+#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);
+	}
+}
+
+void InverstNode(Node **head) {
+	/* empty list */
+	if (*head == NULL) {
+		return;
+	}
+
+	/* only one node in list */
+	if ((*head)->next == NULL) {
+		return;
+	}
+
+	/* reverse Node */
+	Node *a, *b, *c;
+	a = NULL;
+	b = *head;
+	c = (*head)->next;
+
+	/* when c == NULL, b is the end of linked list */
+	while (c) {
+		/* reverse node */
+		b->next = a;
+		/* move a, b, c forward */
+		a = b;
+		b = c;
+		c = c->next;
+	}
+	/* finanl step */
+	b->next = a;
+	/* reset head */
+	*head = b;
+}
+
+void RemoveDuplicates(Node **head) {
+	Node *newHead = NULL, *currNode = *head;
+	double oldValue;
+	int position;
+
+	/* empty list, no need to do anything */
+	if ((*head) == NULL) {
+		return;
+	}
+
+	/* only one node in the list, no need to do anything */
+	if ((*head)->next == NULL) {
+		return;
+	}
+
+	/* loop until currNode point at NULL */
+	while (currNode) {
+		/* check whether there is any same value node after this node */
+		position = FindNode(currNode->next, currNode->data);
+
+		/* position is not 0, means this is the duplicated value */
+		if (position) {
+			/* record current duplicated value */
+			oldValue = currNode->data;
+
+			/* then use a for loop jump pass the duplicated value,
+			 * use for loop to check currNode is not NULL
+			 * before get currNode->data */
+			for (; currNode; currNode=currNode->next) {
+				/* exit when we find a new value */
+				if (currNode->data != oldValue) {
+					break;
+				}
+			}
+
+			continue;
+		}
+
+		/* if this is not a duplicated value,
+		 * add unique node to new linked list */
+		InsertNode(&newHead, 0, currNode->data);
+
+		/* move to next */
+		currNode = currNode->next;
+	}
+
+	/* Inverst to original direction */
+	InverstNode(&newHead);
+	/* reset head, remember to destory old list, avoid memory leak */
+	DestroyList(*head);
+	*head = newHead;
+}