【LeetCode】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.

思路：就是将没有左右节点的叶节点的深度看成1，递归到根节点即可。

/**
* Definition for binary tree
* 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;
TreeNode *lroot,*rroot;
lroot=root->left;
rroot=root->right;
int ldth=0,rdth=0;
if(root->right==NULL&&root->left==NULL){
return 1;
}else if(root->right==NULL){
return (1+minDepth(lroot));
}
else if(root->left==NULL){
return (1+minDepth(rroot));
}else{
ldth=minDepth(lroot);
rdth=minDepth(rroot);
return(1+(ldth<rdth?ldth:rdth));
}
}
};