考研算法

题目

题目链接

题目要求

遍历二叉树
可以使用深度遍历和宽度遍历
深度遍历代码量较小

代码

/**
 * 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 dfs(TreeNode *root,int path)
    {
        if (!root) return 0;//节点是否存在
        if (!root->left and !root->right)//若为叶子节点
        {
            return root->val*path;
        }
        else return dfs(root->left,path+1)+dfs(root->right,path+1);//继续遍历
    }
    int pathSum(TreeNode* root) {
        return dfs(root,0);
    }
};

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

def dfs(root,path):
    if root==None:return 0
    if (root.left==None and root.right==None):
        return root.val*path
    else:
        return dfs(root.left,path+1)+dfs(root.right,path+1)
class Solution:
    def pathSum(self, root):
        """
        :type root: TreeNode
        :rtype: int
        """
        a=dfs(root,0)
        return a