Minimum Depth of Binary Tree @LeetCode

PROBLEM :

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.

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SIMPLE c++ IMPLEMENTATION :( Using Queue )
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 /**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */

class Solution {
public:
    int minDepth(TreeNode* root) {
        if(root==NULL)
            return 0 ;
         
        queue<TreeNode*> que ;
        que.push(root) ;
        int depth=0 ;
     
        while(!que.empty()){
            int n=que.size() ;
            depth++ ;
         
            while(n--){
                TreeNode* node=que.front() ;
                que.pop() ;
             
                if(node->left==NULL&&node->right==NULL)
                    return depth ;
             
                if(node->left)
                    que.push(node->left) ;
                if(node->right)
                    que.push(node->right) ;
            }
        }
    }
};


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SIMPLE c++ IMPLEMENTATION :( Better Solution )
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/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */

class Solution {
public:
    int minDepth(TreeNode* root) {
        if(root==NULL)
            return 0 ;
         
        int l=minDepth(root->left) ;
        int r=minDepth(root->right) ;
     
        return (l==0||r==0)?l+r+1:(l<r?l+1:r+1) ;
    }
};

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