minimum-depth-of-binary-tree-02-02-2025.cc

/**
 * Definition for a binary tree node.
 * 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) {}
 * };
 */
 
#include <queue>
#include <utility>
 
class Solution {
public:
 
    // Breadth First Search
    int minDepth(TreeNode* root) {
        if (!root) { return 0; }
 
        std::queue<std::pair<TreeNode*, int>> bfsQ;
        bfsQ.push({root, 1});
 
        while (!bfsQ.empty()) {
            TreeNode* node = bfsQ.front().first;
            int depth = bfsQ.front().second;
 
            bfsQ.pop();
 
            // If leaf node, return depth
            if (!node->left && !node->right) { return depth; }
 
            if (node->left) { bfsQ.push({ node->left, depth + 1 }); }
            if (node->right) { bfsQ.push({ node->right, depth + 1 }); }
        }
 
        return 0;
    }
};