The minimum depth of a binary tree NO.111

Given a binary tree, to find out the minimum depth.

Minimum depth is the number of nodes in the shortest path from the root node to leaf nodes nearest.

Description: leaf node is a node has no child nodes.

Example:

Given binary tree [3,9,20, null, null, 15,7],

    3
   / \
  9  20
    /  \
   15   7

2 returns to its minimum depth.

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */


int DFS(struct TreeNode* root)
{
    if(!root)return 0;
    int left=0,right=0;
    if(root->left)left=DFS(root->left);
    if(root->right)right=DFS(root->right);
    if(left==0)return right+1;
    else if(right==0)return left+1;
    else return left<right?left+1:right+1;
}

int minDepth(struct TreeNode* root){
    if(!root)return 0;
    return DFS(root);
}

When execution: 16 ms, beat the 91.63% of all users in C submission

Memory consumption: 9.9 MB, defeated 100.00% of all users in C submission