From a20e4340e44f4155ee0ad08146585086d46e061c Mon Sep 17 00:00:00 2001
From: Mahmoud Hamed <63455983+MHamiid@users.noreply.github.com>
Date: Wed, 14 Dec 2022 04:47:02 +0200
Subject: [PATCH] Create 297-Serialize-and-Deserialize-Binary-Tree.c

Create the C solution as the same solution in the YouTube video "https://www.youtube.com/watch?v=u4JAi2JJhI8"
---
 c/297-Serialize-and-Deserialize-Binary-Tree.c | 88 +++++++++++++++++++
 1 file changed, 88 insertions(+)
 create mode 100644 c/297-Serialize-and-Deserialize-Binary-Tree.c

diff --git a/c/297-Serialize-and-Deserialize-Binary-Tree.c b/c/297-Serialize-and-Deserialize-Binary-Tree.c
new file mode 100644
index 000000000..60875f7cc
--- /dev/null
+++ b/c/297-Serialize-and-Deserialize-Binary-Tree.c
@@ -0,0 +1,88 @@
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     struct TreeNode *left;
+ *     struct TreeNode *right;
+ * };
+ */
+#define DATA_ALLOCATION_SIZE 10000
+
+typedef struct TreeNode TreeNode;
+
+void dfs_encode(TreeNode* node, char** data, int* dataIndex, int* dataSize)
+{
+    // Check if new space reallocation is needed
+    if((*dataIndex) + 10 >= *dataSize)  // (+10) to add a little bit of margin for any data to be written in this function scope
+    {
+        // Reallocate data string for a bigger space
+        *dataSize += DATA_ALLOCATION_SIZE;
+        *data = (char*)realloc(*data, *dataSize * sizeof(char));
+    }
+
+    if(!node)
+    {
+        (*data)[(*dataIndex)++] = 'N';
+        (*data)[(*dataIndex)++] = ',';
+        return;
+    }
+
+    // Returns total number of characters written is returned excluding the null-character 
+    int charsWritten = sprintf(*data + *dataIndex, "%d", node->val);
+    *dataIndex += charsWritten;
+    (*data)[(*dataIndex)++] = ',';     // This is actually is written in-place of the null terminator
+
+    dfs_encode(node->left, data, dataIndex, dataSize);
+    dfs_encode(node->right, data, dataIndex, dataSize);
+}
+
+TreeNode* dfs_decode(char** data)
+{
+    // Reached end of the string
+    if((*data)[0] == '\0')
+    {
+        return NULL;
+    }
+    else if((*data)[0] == 'N')
+    {
+        // Skip two chars ('N' and ',')
+        *data += 2;
+        return NULL;
+    }
+
+    TreeNode* node = (TreeNode*)malloc(sizeof(TreeNode));
+    char* endPtr = NULL; // Points to the first char after the numeric value
+
+    // Set the node value
+    node->val = strtol(*data, &endPtr, 10);
+    *data = endPtr + 1;  // (+1) to skip the ','
+
+    node->left = dfs_decode(data);
+    node->right = dfs_decode(data);
+    
+    return node;
+}
+
+/** Encodes a tree to a single string. */
+char* serialize(struct TreeNode* root) {
+    // Allocate the maximum possible number of nodes
+    int dataSize = DATA_ALLOCATION_SIZE;
+    char* data = (char*)malloc(dataSize * sizeof(char));
+    int dataIndex = 0;  // points to the first empty space in the data string
+
+    dfs_encode(root, &data, &dataIndex, &dataSize);
+    // Add the null terminator
+    data[dataIndex] = '\0';
+
+    return data;
+}
+
+/** Decodes your encoded data to tree. */
+struct TreeNode* deserialize(char* data) {
+
+    return dfs_decode(&data);
+}
+
+// Your functions will be called as such:
+// char* data = serialize(root);
+// deserialize(data);