LeetCode 111. Minimum Depth of Binary Tree

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.

/**
 * 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;
        else if(root->left == NULL && root->right == NULL)
            return 1;
        else if(root->left == NULL && root->right != NULL)
            return minDepth(root->right) + 1;
        else if(root->right == NULL && root->left != NULL)
            return minDepth(root->left) + 1;
        else {
            int leftdepth = minDepth(root->left);
            int rightdepth = minDepth(root->right);
            return leftdepth < rightdepth ? leftdepth + 1 : rightdepth + 1;
        }
    }
};

/**

* 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;

else if(root->left == NULL && root->right == NULL)

return 1;

else if(root->left == NULL && root->right != NULL)

return minDepth(root->right) + 1;

else if(root->right == NULL && root->left != NULL)

return minDepth(root->left) + 1;

else {

int leftdepth = minDepth(root->left);

int rightdepth = minDepth(root->right);

return leftdepth < rightdepth ? leftdepth + 1 : rightdepth + 1;

}

};

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