leetcode

利用BFS，遇到的第一个叶子节点的当前深度即为最小深度。

代码

class Solution {
public:
    int minDepth(TreeNode *root) {
        if(root==NULL)
          return 0;
        TreeNode *p;
        p = root;
        minNum = 0;
        queue<TreeNode*> queue_push, queue_pop;
        queue_pop.push(p);
       
        while(!queue_pop.empty())
        {
            TreeNode *tempNode;
            tempNode = queue_pop.front();
            queue_pop.pop();
            
            if(!tempNode->left&&!tempNode->right)
                return ++minNum;
            
            if(tempNode->left)
                queue_push.push(tempNode->left);
            if(tempNode->right)
                queue_push.push(tempNode->right);
       
            if(queue_pop.empty())
            {
               minNum++;
               swap(queue_pop, queue_push);
            }
            
        }
        
        return minNum;
        
    }
    
private:
    int minNum;
};