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SerializeDeserializeNAryTree.ts
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SerializeDeserializeNAryTree.ts
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/**
* Definition for node.
* class Node {
* val: number
* children: Node[]
* constructor(val?: number) {
* this.val = (val===undefined ? 0 : val)
* this.children = []
* }
* }
*/
/**
* Problem: Leet Code 428
* Solution: Uses the depth 1st traversal to serialize and deserialize the N-Ary tree. The ser and deser process
* uses a special marker with null(empty string) to determine that the current branch has ended. This helps us
* determine, that we have to backtrack and start adding new elements to the parents childs and so on.
*
* Time: O(n) since all the nodes needs to be traversed at least once. Spsace: O(n) since at least additional space
* of n items is required.
*
*/
class Codec {
constructor() {
}
// Encodes a tree to a single string.
serialize(root: Node | null): string {
const serialized: string[] = []
this.serializeHelper(root, serialized);
return serialized.join(";");
};
serializeHelper(root: Node | null, serialized: string[]) {
if (root === null) return
serialized.push(root.val.toString())
if (root.children.length === 0) {
// Found a leaf node, ending a terminating null;
serialized.push("")
} else {
root.children.forEach(child => this.serializeHelper(child, serialized));
serialized.push("")
}
}
// Decodes your encoded data to tree.
deserialize(data: string): Node | null {
const elements = data.split(";")
return this.deserializeHelper(elements);
};
deserializeHelper(elements: string[]): Node | null {
const value = elements.shift();
if (value === undefined || value === "") return null;
const root = new Node(parseInt(value));
let child;
while ( (child = this.deserializeHelper(elements)) !== null) {
root.children.push(child)
}
return root;
}
}
// Your Codec object will be instantiated and called as such:
// Codec codec = new Codec();
// codec.deserialize(codec.serialize(root));