题目描述
请实现两个函数,分别用来序列化和反序列化二叉树
二叉树序列化
我们以前序遍历的顺序进行序列化,对于空结点我们用一个特殊的符号‘$’来代替,则序列化后的字符串为“1 2 4 $ $ 5 $ $ 3 6 $ $ 7 $ $”
数组vector<int>:1 2 4 0xFFFFFFFF 0xFFFFFFFF 5 0xFFFFFFFF 0xFFFFFFFF 3 6 0xFFFFFFFF 0xFFFFFFFF 7 0xFFFFFFFF 0xFFFFFFFF
/*
struct TreeNode {
int val;
struct TreeNode *left;
struct TreeNode *right;
TreeNode(int x) :
val(x), left(NULL), right(NULL) {
}
};
*/
class Solution {
public:
//序列化,深度优先遍历(先序遍历)
vector<int> buf;
void dfs1(TreeNode *root){
if(!root) buf.push_back(0xFFFFFFFF);
else{
buf.push_back(root->val);
dfs1(root->left);
dfs1(root->right);
}
}
char* Serialize(TreeNode *root){
buf.clear();
dfs1(root);
int *res=new int[buf.size()];
for(int i=0;i<buf.size();++i) res[i]=buf[i];
return (char*)res;
}
TreeNode* dfs2(int * &p){
if(*p==0xFFFFFFFF){
p++;
return nullptr;
}
TreeNode *node=new TreeNode(*p);
p++;
node->left=dfs2(p);
node->right=dfs2(p);
return node;
}
TreeNode* Deserialize(char *str){
int *p=(int*)str;
return dfs2(p);
}
/*
vector<int> buf;
//按深度优先遍历
void dfs1(TreeNode *root) {
if(!root) buf.push_back(0xFFFFFFFF);
else {
buf.push_back(root->val);
dfs1(root->left);
dfs1(root->right);
}
}
TreeNode* dfs2(int* &p) {
if(*p==0xFFFFFFFF) {
p++;
return NULL;
}
TreeNode* res=new TreeNode(*p);
p++;
res->left=dfs2(p);
res->right=dfs2(p);
return res;
}
char* Serialize(TreeNode *root) {//序列化
buf.clear();
dfs1(root);
int bufSize=buf.size();
int *res=new int[bufSize];
for(int i=0;i<bufSize;i++) res[i]=buf[i];
return (char*)res;
}
TreeNode* Deserialize(char *str) {//反序列化
int *p=(int*)str;
return dfs2(p);
}
*/
/*
//=========================二叉树序列化==============前序遍历================
char* Serialize(TreeNode *root) {
if (root == NULL)
return NULL;
string str;
serialize(root, str);
char* buffer = new char[str.size() + 1];
strcpy(buffer, str.c_str());//将string类型的字符串转换成C_style类型并复制到一个char类型数组
return buffer;
}
void serialize(TreeNode* root, string& str)
{
if (root == NULL)
{
str += "$,";//叶子结点的左右子结点为空则用 $ 来代替
return;
}
str += to_string(root->val);//将结点值(int)转换成字符串(string)类型
str += ',';
serialize(root->left, str);//递归序列化结点的左子树
serialize(root->right, str);//递归序列化结点的右子树
}
//========================二叉树反序列化============================
TreeNode* Deserialize(char *str) {
if (str == NULL)
return NULL;
return deserialize(&str);
}
TreeNode* deserialize(char** str)
{
if (**str == '$')
{
(*str) += 2;
return NULL;
}
int val = 0;
while (**str != ','&&**str != '\0')//把字符串类型的数字转换成int类型的数字
{
val = val * 10 + (**str - '0');
++(*str);
}
TreeNode* root = new TreeNode(val);//构建根结点
if (**str == '\0')
return root;
else
++(*str);
root->left = deserialize(str);//递归的构建左子树结点
root->right = deserialize(str);//递归的构建右子树结点
return root;
}
*/
};