Minimum Depth of a Binary Tree

Given a binary tree, find its minimum depth.

• Time : O(n)
• Space : O(1)

/* The Node structure is
struct Node
{
    int data;
    Node* left;
    Node* right;
}; */

class Solution{
  public:
    /*You are required to complete this method*/
    int minDepth(Node *root, int dep = 1) {
        if(!root->left and !root->right) return dep;
        int res = INT_MAX;
        if(root->left) res = min(res, minDepth(root->left, dep + 1));
        if(root->right) res = min(res, minDepth(root->right, dep + 1));
        return res;
    }
};