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[LeetCode] Maximum Depth of Binary Tree

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Given a binary tree, find its maximum depth.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

 

     这道题我们借助stack和iteration就可以做出来了。

     一个stack<TreeNode>用于node,另一个stack<Integer>用于depth的value。

     代码如下。~

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public int maxDepth(TreeNode root) {
        Stack<TreeNode> tree=new Stack<TreeNode>();
        Stack<Integer> value=new Stack<Integer>();
        int max=0;
        if(root==null){
            return 0;
        }
        tree.push(root);
        value.push(1);
        while(!tree.isEmpty()){
            TreeNode temp=tree.pop();
            int val=value.pop();
            max=Math.max(max,val);
            if(temp.right!=null){
                tree.push(temp.right);
                value.push(val+1);
            }
            if(temp.left!=null){
                tree.push(temp.left);
                value.push(val+1);
            }
        }
        return max;
    }
}

 

    

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