From e5efa02c2746a4207251daf0173b4808dd087e89 Mon Sep 17 00:00:00 2001
From: leiyu3 <s444814187@gmail.com>
Date: Tue, 13 Sep 2022 18:11:37 -0400
Subject: init

---
 liblinked_list.c | 179 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 179 insertions(+)
 create mode 100644 liblinked_list.c

(limited to 'liblinked_list.c')

diff --git a/liblinked_list.c b/liblinked_list.c
new file mode 100644
index 0000000..83689a5
--- /dev/null
+++ b/liblinked_list.c
@@ -0,0 +1,179 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "linked_list.h"
+
+int count_ll(node* ptr){
+    /*
+    Count the number of nodes in a linked list.
+   */
+    // TODO:: What if there is 0 item in the linked list??
+    int count = 0;
+    while (ptr != NULL){
+        count++;
+        ptr = ptr->next;
+    }
+    return count;
+}
+
+void prepend_ll(node **ptr, int value){
+    /*
+    Add a node to the front of the linked list
+   */
+    node* new = malloc(sizeof(node));
+    new->value = value;
+    new->next = *ptr;
+    *ptr = new;
+
+}
+
+void append_ll(node* ptr, int value){
+    /*
+       Add a node to the end of the linked list
+   */
+    node* new = malloc(sizeof(node));
+    new->value = value;
+    new->next = NULL;
+    while (ptr->next != NULL){
+        ptr = ptr->next;
+    }
+    ptr->next = new;
+}
+
+void print_ll(node* ptr){
+    /*
+       Print out the linked list
+   */
+    while (ptr != NULL){
+        printf("%d", ptr->value);
+        ptr = ptr->next;
+        if (ptr == NULL){
+            break;
+        }
+        printf(" - ");
+    }
+    printf("\n");
+}
+
+void free_ll(node* ptr){
+    /*
+       Safely free all nodes inside linked list.
+   */
+    node* next;
+    while (ptr->next != NULL){
+        next = ptr->next;
+        free(ptr);
+        ptr = next;
+    }
+}
+
+int update_node(node* ptr, int index, int value){
+    /*
+       Update value of a node inside linked list
+   */
+    // TODO:: What if the index is out of range?
+
+    if (index >= count_ll(ptr)){
+        // index out of range
+        return 1;
+    }
+
+    int count = 0;
+    while (count < index){
+        ptr = ptr->next;
+        count++;
+    }
+
+    ptr->value = value;
+    return 0;
+}
+
+int delete_node(node **ptr, int index){
+    /*
+       Delete a node given the index
+   */
+
+    // TODO:: What if the node doesn't exist?
+    node* prev;
+    if (index == 0){
+        prev = *ptr;
+        *ptr = (*ptr)->next;
+        free(prev);
+        return 0;
+    }
+
+    node* root = *ptr;
+    for (int i = 0; i <= index; i++){
+        if (i == index){
+            prev->next = root->next;
+            free(root);
+            return 0;
+        }
+        prev = root;
+        root = root->next;
+    }
+    
+    printf("Node not found\n");
+    exit(-1);
+}
+
+int get_value(node *ptr, int index){
+    /*
+        Get the value of a specific node given the index
+   */
+    // TODO:: What if the index is out of range??
+
+    for (int i = 0; i < index; i++){
+        ptr = ptr->next;
+    }
+    return ptr->value;
+
+}
+
+node* search_node(node *ptr, int value){
+    /*
+        Search for a node given the value and returns it
+    */
+
+    while (1){
+        if (ptr == NULL){
+            fprintf(stderr, "Value doesn't exitst in linked list\n");
+            exit(-1);
+        }
+        if (ptr->value == value){
+            break;
+        }
+        ptr = ptr->next;
+    }
+    return ptr;
+}
+
+void reverse_ll(node** ptr){
+    node *prev, *cur, *next;
+    int n = count_ll(*ptr);
+
+    if (n == 0){
+        return;
+    }
+
+    if (n == 1){
+        return;
+    }
+    
+    prev = *ptr;
+    cur = prev->next; 
+    next = cur->next;
+    prev->next = NULL;
+
+    cur->next = prev;
+
+    for (int i = 0; i < n-2; i++){
+        prev = cur;
+        cur = next;
+        next = next->next;
+        cur->next = prev;
+    }
+
+
+    *ptr = cur;
+}
+
-- 
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