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{"@context":"https://schema.org","@type":"Code","url":"https://leetcodejavascript.com/solutions/validate-binary-tree-nodes","name":"#1361 - Validate Binary Tree Nodes - LeetCode JavaScript Solutions","description":"You have n binary tree nodes numbered from 0 to n - 1 where node i has two children leftChild[i] and rightChild[i], return true if and only ...","programmingLanguage":"JavaScript","codeRepository":"https://github.com/JoshCrozier/leetcode-javascript","codeSampleType":"JavaScript","text":"/**\n * @param {number} n\n * @param {number[]} leftChild\n * @param {number[]} rightChild\n * @return {boolean}\n */\nvar validateBinaryTreeNodes = function(n, leftChild, rightChild) {\n  const parentCount = new Array(n).fill(0);\n  let rootCandidate = -1;\n\n  for (let i = 0; i < n; i++) {\n    if (leftChild[i] !== -1) parentCount[leftChild[i]]++;\n    if (rightChild[i] !== -1) parentCount[rightChild[i]]++;\n  }\n\n  for (let i = 0; i < n; i++) {\n    if (parentCount[i] === 0) {\n      if (rootCandidate !== -1) return false;\n      rootCandidate = i;\n    }\n    if (parentCount[i] > 1) return false;\n  }\n\n  if (rootCandidate === -1) return false;\n\n  return countNodes(rootCandidate, new Set()) === n;\n\n  function countNodes(node, visited) {\n    if (node === -1) return 0;\n    if (visited.has(node)) return -1;\n    visited.add(node);\n    const leftNodes = countNodes(leftChild[node], visited);\n    const rightNodes = countNodes(rightChild[node], visited);\n    if (leftNodes === -1 || rightNodes === -1) return -1;\n    return 1 + leftNodes + rightNodes;\n  }\n};","keywords":"LeetCode 1361, #1361 - Validate Binary Tree Nodes, Medium, JavaScript solution","learningResourceType":"Code","isAccessibleForFree":true,"educationalLevel":"intermediate","interactivityType":"mixed"}