层序遍历实现
/*
// Definition for a Node.
class Node {
public:
int val;
Node* left;
Node* right;
Node* next;
Node() : val(0), left(NULL), right(NULL), next(NULL) {}
Node(int _val) : val(_val), left(NULL), right(NULL), next(NULL) {}
Node(int _val, Node* _left, Node* _right, Node* _next)
: val(_val), left(_left), right(_right), next(_next) {}
};
*/
class Solution {
public:
Node* connect(Node* root) {
queue<Node*> q;
if(root == nullptr) return root;
q.push(root);
while(!q.empty()){
int len = q.size();
for(int i = 0;i<len;i++){
Node* node = q.front();
q.pop();
if(i<len-1) node->next = q.front();
if(node->left) q.push(node->left);
if(node->right) q.push(node->right);
}
}
return root;
}
};
递归
/*
// Definition for a Node.
class Node {
public:
int val;
Node* left;
Node* right;
Node* next;
Node() : val(0), left(NULL), right(NULL), next(NULL) {}
Node(int _val) : val(_val), left(NULL), right(NULL), next(NULL) {}
Node(int _val, Node* _left, Node* _right, Node* _next)
: val(_val), left(_left), right(_right), next(_next) {}
};
*/
class Solution {
public:
Node* connect(Node* root) {
if(root == nullptr) return root;
if(root->left){
root->left->next = root->right;
if(root->next){
root->right->next = root->next->left;
}
}
connect(root->left);
connect(root->right);
return root;
}
};