Minimum Depth of Binary Tree Problem & Solution
Given a binary tree, find its minimum depth. The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node. A leaf is a node with no children.
See the minimum depth of binary tree problem on LeetCode.
C++ Solution
#pragma GCC optimize("Ofast")
#pragma GCC optimization("max-inline-insns-recursive-auto")
static const int _=[](){std::ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);return 0;}();
/**
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
int minDepth(TreeNode* root) {
if (root == nullptr) {
return 0;
}
int result = INT_MAX;
minDepth(root, 0, result);
return result;
}
private:
void minDepth(TreeNode* root, int depth, int& result) {
if (root == nullptr) {
return;
}
if (root->left == nullptr && root->right == nullptr) {
result = min(result, depth + 1);
}
minDepth(root->left, depth + 1, result);
minDepth(root->right, depth + 1, result);
}
};