层次遍历
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| class Solution {
public:
Node* connect(Node* root) {
queue<Node*> q;
if(root)
q.push(root);
Node* pre = nullptr;
while(q.size()) {
int sz = q.size();
for(int i = 0; i < sz; ++i) {
Node* node = q.front();
q.pop();
if(node->left) {
q.push(node->left);
}
if(node->right) {
q.push(node->right);
}
if(!pre) {
pre = node;
} else {
pre->next = node;
pre = node;
}
}
pre = nullptr;
}
return root;
}
};
|
Accepted
55/55 cases passed (8 ms)
Your runtime beats 99.5 % of cpp submissions
Your memory usage beats 34.56 % of cpp submissions (20.1 MB)
递归
重点在于：需要从右边往左边递归。
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| class Solution {
public:
Node* connect(Node* root) {
if(root && (root->left || root->right)) {
if(root->left && root->right)
root->left->next = root->right;
Node* node = root->right ? root->right : root->left;
Node* head = root->next;
while(head && !head->left && !head->right) {
head = head->next;
}
node->next = !head ? nullptr : head->left ? head->left : head->right;
connect(root->right);
connect(root->left);
}
return root;
}
};
|
Accepted
55/55 cases passed (16 ms)
Your runtime beats 85.93 % of cpp submissions
Your memory usage beats 35.68 % of cpp submissions (20 MB)
