Add C++ implementation

Signed-off-by: begeekmyfriend <begeekmyfriend@gmail.com>

Author: begeekmyfriend

0297_serialize_and_deserialize_binary_tree/Makefile

@@ -0,0 +1,2 @@
+all:
+	gcc -O1 -o test tree_serdes.c

0297_serialize_and_deserialize_binary_tree/tree_serdes.c

@@ -0,0 +1,114 @@
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+
+struct TreeNode {
+    int val;
+    struct TreeNode *left;
+    struct TreeNode *right;
+};
+
+static void ser(struct TreeNode *root, char **str, int *len) {
+    if (root == NULL) {
+        (*str)[(*len)++] = '#';
+        (*str)[(*len)++] = ',';
+    } else {
+        int v = root->val;
+        if (v < 0) {
+            v = -v;
+            (*str)[(*len)++] = '-';
+        }
+        while (v > 0) {
+            (*str)[(*len)++] = v % 10 + '0';
+            v /= 10;
+        }
+        (*str)[(*len)++] = ',';
+        ser(root->left, str, len);
+        ser(root->right, str, len);
+    }
+}
+
+static struct TreeNode *des(char **str) {
+    if (**str == '\0') {
+        return NULL;
+    }
+    if (**str == '#') {
+        (*str)++;
+        (*str)++;
+        return NULL;
+    }
+
+    int i;
+    bool sign = false;
+    struct TreeNode *node = malloc(sizeof(struct TreeNode));
+    node->val = 0;
+    if (**str == '-') {
+        sign = true;
+        (*str)++;
+    }
+    for (i = 1; **str != ','; i *= 10) {
+        node->val += i * ((**str) - '0');
+        (*str)++;
+    }
+    if (sign) {
+        node->val = -node->val;
+    }
+    (*str)++;
+    node->left = des(str);
+    node->right = des(str);    
+    return node;
+}
+
+/** Encodes a tree to a single string. */
+char* serialize(struct TreeNode* root) {
+    int len = 0;
+    char *str = malloc(40000);
+    memset(str, '\0', 40000);
+    ser(root, &str, &len);
+    return str;
+}
+
+/** Decodes your encoded data to tree. */
+struct TreeNode* deserialize(char* data) {
+    return des(&data);
+}
+
+int main(void)
+{
+    struct TreeNode root;
+    root.val = 3;
+
+    struct TreeNode node1[2];
+    node1[0].val = 9;
+    node1[1].val = 20;
+
+    struct TreeNode node2[4];
+    node2[2].val = 15;
+    node2[3].val = 7;
+
+    root.left = &node1[0];
+    root.right = &node1[1];
+
+    node1[0].left = NULL;
+    node1[0].right = NULL;
+    node1[1].left = &node2[2];
+    node1[1].right = &node2[3];
+
+    node2[0].left = NULL;
+    node2[0].right = NULL;
+    node2[1].left = NULL;
+    node2[1].right = NULL;
+    node2[2].left = NULL;
+    node2[2].right = NULL;
+    node2[3].left = NULL;
+    node2[3].right = NULL;
+
+    /* Your functions will be called as such */
+    char* data = serialize(&root);
+    printf("%s\n", data);
+    deserialize(data);
+
+    return 0;
+}