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import { concat, sum } from './array';
export type Tree<T> = {
node: T,
children: Forest<T>;
};
export type Forest<T> = Tree<T>[];
export function createLeaf<T>(node: T): Tree<T> {
return { node, children: [] };
}
export function createTree<T>(node: T, children: Forest<T>): Tree<T> {
return { node, children };
}
export function hasChildren<T>(t: Tree<T>): boolean {
return t.children.length !== 0;
}
export function preorder<T>(t: Tree<T>): T[] {
return [t.node, ...preorderF(t.children)];
}
export function preorderF<T>(ts: Forest<T>): T[] {
return concat(ts.map(preorder));
}
export function countNodes<T>(t: Tree<T>): number {
return preorder(t).length;
}
export function countNodesF<T>(ts: Forest<T>): number {
return sum(ts.map(countNodes));
}
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