10 posts tagged with "binaryTree"

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} p
 * @param {TreeNode} q
 * @return {boolean}
 */
var isSameTree = function (p, q) {
  if (p === null && q === null) {
    return true;
  }

  if ((p !== null && q === null) || (p === null && q !== null)) {
    return false;
  }

  if (p.val !== q.val) {
    return false;
  }

  return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
};

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {boolean}
 */
var isSymmetric = function (root) {
  return root === null || isMirrorValue(root.left, root.right);
};

const isMirrorValue = (left, right) => {
  if (left === null && right === null) {
    return true;
  }
  if (left === null || right === null) {
    return false;
  }

  if (left.val === right.val) {
    return (
      isMirrorValue(left.right, right.left) &&
      isMirrorValue(left.left, right.right)
    );
  } else {
    return false;
  }
};

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number}
 */
var maxDepth = function (root) {
  if (root === null) {
    return 0;
  }

  return 1 + Math.max(maxDepth(root.left), maxDepth(root.right));
};

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {number[]} nums
 * @return {TreeNode}
 */
var sortedArrayToBST = function (nums) {
  if (nums.length === 0) {
    return null;
  }
  return createBST(nums, 0, nums.length - 1);
};

const createBST = (nums, low, high) => {
  if (low > high) {
    return null;
  }

  let mid = Math.floor((high + low) / 2);

  let node = new TreeNode(nums[mid]);
  node.left = createBST(nums, low, mid - 1);
  node.right = createBST(nums, mid + 1, high);
  return node;
};

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {boolean}
 */
var isBalanced = function (root) {
  if (root === null) {
    return true;
  }
  return checkDepth(root) !== false;
};

const checkDepth = (node) => {
  if (node === null) {
    return 0;
  }

  // 각각 false 혹은 왼쪽/오른쪽 자식의 최대 깊이
  const left = checkDepth(node.left);
  const right = checkDepth(node.right);

  if (left === false || right === false || Math.abs(left - right) > 1) {
    return false;
  }

  // 트리의 가장 깊은 길이를 return
  return Math.max(left, right) + 1;
};

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number}
 */
var minDepth = function (root) {
  if (root === null) {
    return 0;
  }

  if (root.left === null) {
    return minDepth(root.right) + 1;
  }
  if (root.right === null) {
    return minDepth(root.left) + 1;
  }

  return 1 + Math.min(minDepth(root.left), minDepth(root.right));
};

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @param {number} targetSum
 * @return {boolean}
 */
var hasPathSum = function (root, targetSum) {
  if (root === null) {
    return false;
  }

  const calculatedValue = targetSum - root.val;
  if (root.left === null && root.right === null) {
    if (calculatedValue === 0) {
      return true;
    }
    return false;
  }

  return (
    hasPathSum(root.left, calculatedValue) ||
    hasPathSum(root.right, calculatedValue)
  );
};

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number[]}
 */
var preorderTraversal = function (root) {
  let result = [];

  traversalHelper(root, result);

  return result;
};

const traversalHelper = (root, result) => {
  if (root === null) {
    return;
  }
  result.push(root.val);
  traversalHelper(root.left, result);
  traversalHelper(root.right, result);
};

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number[]}
 */
var postorderTraversal = function (root) {
  let result = [];
  traversalHelper(root, result);
  return result;
};

const traversalHelper = (root, result) => {
  if (root === null) {
    return;
  }
  result.unshift(root.val);
  traversalHelper(root.right, result);
  traversalHelper(root.left, result);
};

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number[]}
 */
var inorderTraversal = function (root) {
  let stack = [];
  let result = [];

  while (root !== null || stack.length !== 0) {
    while (root !== null) {
      stack.push(root);
      root = root.left;
    }
    root = stack.pop();
    result.push(root.val);
    root = root.right;
  }
  return result;
};