N-ary Tree Postorder Traversal Traversal Problem & Solution
Given the root of an n-ary tree, return the postorder traversal of its nodes' values.
N-ary tree input serialization is represented in their level order traversal. Each group of children is separated by the null value.
See the n-ary tree postorder traversal problem on LeetCode.
C++ Solution
#pragma GCC optimize("Ofast")
#pragma GCC optimization("unroll-loops")
#pragma GCC optimization("max-inline-insns-recursive-auto")
static const int _=[](){ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);return 0;}();
/*
class Node {
public:
int val;
vector<Node*> children;
Node() {}
Node(int _val) {
val = _val;
}
Node(int _val, vector<Node*> _children) {
val = _val;
children = _children;
}
};
*/
class Solution {
public:
vector<int> postorder(Node* root) {
vector<int> traversal;
postorder(root, traversal);
return traversal;
}
private:
void postorder(Node* node, vector<int>& traversal) {
if (node == nullptr) {
return;
}
for (int i = 0; i < node->children.size(); ++i) {
postorder(node->children[i], traversal);
}
traversal.push_back(node->val);
}
};