Minimum Depth of Binary Tree--LeetCode

题目：

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：这里递归就需要注意一些东西了，对于非递归来说，只要发现有一个节点没有左子树同时也没有右子树，那么这个就是节点所在层次就是目标

int MinDepth(BinTree* root){if(root == NULL)return 0;if(root->left == NULL)return MinDepth(root->right)+1;if(root->right == NULL)return MinDepth(root->left)+1;return min(MinDepth(root->left),MinDepth(root->right))+1;}int MinDepth_second(BinTree* root){if(root == NULL)return 0;BinTree* node;deque<BinTree*> de;int num;int curnum=0;int level=0;de.push_back(root);num=1;while(!de.empty()) {node = de.front();de.pop_front();num--;if(node->left==NULL && node->right == NULL)return level+1;if(node->left != NULL){de.push_back(node->left);curnum++;}if(node->right !=NULL){de.push_back(node->right);curnum++;}if(num == 0){num = curnum;curnum=0;level++;}}return level;}