2024-02-28 Daily Challenge

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In: DailyChallenge
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Today I have done leetcode's February LeetCoding Challenge with cpp.

February LeetCoding Challenge 28

Description

Find Bottom Left Tree Value

Given the root of a binary tree, return the leftmost value in the last row of the tree.

 

Example 1:

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

Example 2:

Input: root = [1,2,3,4,null,5,6,null,null,7]
Output: 7

 

Constraints:

  • The number of nodes in the tree is in the range [1, 104].
  • -231 <= Node.val <= 231 - 1

Solution

auto speedup = [](){
  cin.tie(nullptr);
  cout.tie(nullptr);
  ios::sync_with_stdio(false);
  return 0;
}();
class Solution {
  pair<int, int> solve(TreeNode *root, int level) {
    if(!root) return {-1, -1};
    auto [llevel, lvalue] = solve(root->left, level + 1);
    auto [rlevel, rvalue] = solve(root->right, level + 1);
    if(llevel == -1 && rlevel == -1) return {level, root->val};
    if(llevel >= rlevel) return {llevel, lvalue};
    return {rlevel, rvalue};
  }
public:
  int findBottomLeftValue(TreeNode* root) {
    return solve(root, 0).second;
  }
};

// Accepted
// 77/77 cases passed (11 ms)
// Your runtime beats 42.78 % of cpp submissions
// Your memory usage beats 96.27 % of cpp submissions (20 MB)
Algorithm