TreeNode.ts

TreeNode.ts

/**
 * Definition for a binary tree node.
 * class TreeNode {
 *     val: number
 *     left: TreeNode | null
 *     right: TreeNode | null
 *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
 *         this.val = (val===undefined ? 0 : val)
 *         this.left = (left===undefined ? null : left)
 *         this.right = (right===undefined ? null : right)
 *     }
 * }
 */
export class TreeNode {
    val: number;
    left: TreeNode | null;
    right: TreeNode | null;

    constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
        this.val = val === undefined ? 0 : val;
        this.left = left === undefined ? null : left;
        this.right = right === undefined ? null : right;
    }

    static fromArray(arr: number[]): TreeNode {
        if (arr.length === 0) {
            return null;
        }

        return this.createByIndex(arr, 0);
    }

    private static createByIndex(arr: number[], index: number): TreeNode {
        if (index >= arr.length || arr[index] === null) {
            return null;
        }

        const val = arr[index];
        const left = this.createByIndex(arr, index * 2 + 1);
        const right = this.createByIndex(arr, index * 2 + 2);

        return new TreeNode(val, left, right);
    }

    toArray() {
        const res = [];
        const root = this;
        let current = new Set<[TreeNode, number]>([[root, 0]]);

        while (current.size !== 0) {
            const next = new Set<[TreeNode, number]>();

            current.forEach(([{ val, left, right }, index]) => {
                res[index] = val;
                if (left) {
                    next.add([left, index * 2 + 1]);
                }

                if (right) {
                    next.add([right, index * 2 + 2]);
                }
            });

            current = next;
        }

        for (let i = 0; i < res.length; i++) {
            if (res[i] === undefined) {
                res[i] = null;
            }
        }

        return res;
    }

    validate(expected: number[]) {
        const arr = this.toArray();
        const maxLen = Math.max(arr.length, expected.length);
        let correct = true;
        for (let i = 0; i < maxLen; i++) {
            const isOk = arr[i] === expected[i] ? '✅' : '❌';
            if (!isOk) {
                correct = false;
            }
            console.log(`${isOk} ${arr[i]} ${expected[i]}`);
        }
        return correct;
    }

    print(): string {
        let res = '';
        const arr = this.toArray();
        const levels = this.getLevel(arr.length);

        for (let i = arr.length; i < Math.pow(2, levels + 1); i++) {
            arr[i] = null;
        }

        for (let l = 0; l < levels; l++) {
            const cur = arr.slice(Math.pow(2, l) - 1, Math.pow(2, l + 1) - 1);
            const gap = ' '.repeat(Math.pow(2, levels - l + 1) - 2);
            const shift = ' '.repeat(Math.pow(2, levels - l));
            res += `${shift}${cur.map(this.printValueWithPad).join(gap)}` + '\n';
        }

        console.log(res);
        return res;
    }

    private printValueWithPad (x: number) {
        if (x === null || x === undefined) {
            return '__';
        }

        const space = x < 10 ? ' ' : '';
        return `${space}${x}`;
    }

    private getLevel = (num: number) => {
        let res = 0;

        while (num > 0) {
            num >>= 1;
            res++;
        }

        return res;
    };
}