2021-12-31 Daily-Challenge

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In: DailyChallenge

Today I have done leetcode's December LeetCoding Challenge with cpp.

December LeetCoding Challenge 31

Description

Maximum Difference Between Node and Ancestor

Given the root of a binary tree, find the maximum value v for which there exist different nodes a and b where v = |a.val - b.val| and a is an ancestor of b.

A node a is an ancestor of b if either: any child of a is equal to b or any child of a is an ancestor of b.

Example 1:

img

Input: root = [8,3,10,1,6,null,14,null,null,4,7,13]
Output: 7
Explanation: We have various ancestor-node differences, some of which are given below :
|8 - 3| = 5
|3 - 7| = 4
|8 - 1| = 7
|10 - 13| = 3
Among all possible differences, the maximum value of 7 is obtained by |8 - 1| = 7.

Example 2:

img

Input: root = [1,null,2,null,0,3]
Output: 3

Constraints:

  • The number of nodes in the tree is in the range [2, 5000].
  • 0 <= Node.val <= 10^5

Solution

class Solution {
public:
  int maxAncestorDiff(TreeNode* root, int mmin = INT_MAX, int mmax = INT_MIN) {
    // root node will not be nullptr by constraints
    if(!root) return mmax - mmin;
    mmin = min(mmin, root->val);
    mmax = max(mmax, root->val);
    return max(maxAncestorDiff(root->left, mmin, mmax), maxAncestorDiff(root->right, mmin, mmax));
  }
};

// Accepted
// 27/27 cases passed (4 ms)
// Your runtime beats 81.69 % of cpp submissions
// Your memory usage beats 74.27 % of cpp submissions (9.7 MB)
Algorithm