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)
return 0;
if(root->left==NULL&&root->right==NULL)
return 1;
if(root->left==NULL)
return minDepth(root->right)+1;
else if(root->right==NULL)
return minDepth(root->left)+1;
else
{
return min(minDepth(root->left),minDepth(root->right))+1;
}
}
};