二叉树中所有节点的总和
给出一种求二叉树中所有元素之和的算法。
在上面的二叉树中 sum = 106。
这个想法是递归地调用左子树和,右子树和并将它们的值添加到当前节点的数据中。
C++
/* Program to print sum of all the elements of a binary tree */
#include
using namespace std;
struct Node {
int key;
Node* left, *right;
};
/* utility that allocates a new Node with the given key */
Node* newNode(int key)
{
Node* node = new Node;
node->key = key;
node->left = node->right = NULL;
return (node);
}
/* Function to find sum of all the elements*/
int addBT(Node* root)
{
if (root == NULL)
return 0;
return (root->key + addBT(root->left) + addBT(root->right));
}
/* Driver program to test above functions*/
int main()
{
Node* root = newNode(1);
root->left = newNode(2);
root->right = newNode(3);
root->left->left = newNode(4);
root->left->right = newNode(5);
root->right->left = newNode(6);
root->right->right = newNode(7);
root->right->left->right = newNode(8);
int sum = addBT(root);
cout << "Sum of all the elements is: " << sum << endl;
return 0;
}
Java
// Java Program to print sum of
// all the elements of a binary tree
class GFG
{
static class Node
{
int key;
Node left, right;
}
/* utility that allocates a new
Node with the given key */
static Node newNode(int key)
{
Node node = new Node();
node.key = key;
node.left = node.right = null;
return (node);
}
/* Function to find sum
of all the elements*/
static int addBT(Node root)
{
if (root == null)
return 0;
return (root.key + addBT(root.left) +
addBT(root.right));
}
// Driver Code
public static void main(String args[])
{
Node root = newNode(1);
root.left = newNode(2);
root.right = newNode(3);
root.left.left = newNode(4);
root.left.right = newNode(5);
root.right.left = newNode(6);
root.right.right = newNode(7);
root.right.left.right = newNode(8);
int sum = addBT(root);
System.out.println("Sum of all the elements is: " + sum);
}
}
// This code is contributed by Arnab Kundu
Python3
# Python3 Program to print sum of all
# the elements of a binary tree
# Binary Tree Node
""" utility that allocates a new Node
with the given key """
class newNode:
# Construct to create a new node
def __init__(self, key):
self.key = key
self.left = None
self.right = None
# Function to find sum of all the element
def addBT(root):
if (root == None):
return 0
return (root.key + addBT(root.left) +
addBT(root.right))
# Driver Code
if __name__ == '__main__':
root = newNode(1)
root.left = newNode(2)
root.right = newNode(3)
root.left.left = newNode(4)
root.left.right = newNode(5)
root.right.left = newNode(6)
root.right.right = newNode(7)
root.right.left.right = newNode(8)
sum = addBT(root)
print("Sum of all the nodes is:", sum)
# This code is contributed by
# Shubham Singh(SHUBHAMSINGH10)
C#
using System;
// C# Program to print sum of
// all the elements of a binary tree
public class GFG
{
public class Node
{
public int key;
public Node left, right;
}
/* utility that allocates a new
Node with the given key */
public static Node newNode(int key)
{
Node node = new Node();
node.key = key;
node.left = node.right = null;
return (node);
}
/* Function to find sum
of all the elements*/
public static int addBT(Node root)
{
if (root == null)
{
return 0;
}
return (root.key + addBT(root.left) + addBT(root.right));
}
// Driver Code
public static void Main(string[] args)
{
Node root = newNode(1);
root.left = newNode(2);
root.right = newNode(3);
root.left.left = newNode(4);
root.left.right = newNode(5);
root.right.left = newNode(6);
root.right.right = newNode(7);
root.right.left.right = newNode(8);
int sum = addBT(root);
Console.WriteLine("Sum of all the elements is: " + sum);
}
}
// This code is contributed by Shrikant13
Javascript
C++
#include
#include
using namespace std;
struct Node {
int key;
struct Node *left, *right;
};
// Utility function to create a new node
Node* newNode(int key)
{
Node* temp = new Node;
temp->key = key;
temp->left = temp->right = NULL;
return (temp);
}
/*Function to find sum of all elements*/
int sumBT(Node* root)
{
//sum variable to track the sum of
//all variables.
int sum = 0;
queue q;
//Pushing the first level.
q.push(root);
//Pushing elements at each level from
//the tree.
while (!q.empty()) {
Node* temp = q.front();
q.pop();
//After popping each element from queue
//add its data to the sum variable.
sum += temp->key;
if (temp->left) {
q.push(temp->left);
}
if (temp->right) {
q.push(temp->right);
}
}
return sum;
}
// Driver program
int main()
{
// Let us create Binary Tree shown in above example
Node* root = newNode(1);
root->left = newNode(2);
root->right = newNode(3);
root->left->left = newNode(4);
root->left->right = newNode(5);
root->right->left = newNode(6);
root->right->right = newNode(7);
root->right->left->right = newNode(8);
cout << "Sum of all elements in the binary tree is: "
<< sumBT(root);
}
//This code is contributed by Sarthak Delori
输出
Sum of all the elements is: 36
方法 2 -解决此问题的另一种方法是使用级别顺序遍历。每次从队列中删除节点时,将其添加到 sum 变量中。
C++
#include
#include
using namespace std;
struct Node {
int key;
struct Node *left, *right;
};
// Utility function to create a new node
Node* newNode(int key)
{
Node* temp = new Node;
temp->key = key;
temp->left = temp->right = NULL;
return (temp);
}
/*Function to find sum of all elements*/
int sumBT(Node* root)
{
//sum variable to track the sum of
//all variables.
int sum = 0;
queue q;
//Pushing the first level.
q.push(root);
//Pushing elements at each level from
//the tree.
while (!q.empty()) {
Node* temp = q.front();
q.pop();
//After popping each element from queue
//add its data to the sum variable.
sum += temp->key;
if (temp->left) {
q.push(temp->left);
}
if (temp->right) {
q.push(temp->right);
}
}
return sum;
}
// Driver program
int main()
{
// Let us create Binary Tree shown in above example
Node* root = newNode(1);
root->left = newNode(2);
root->right = newNode(3);
root->left->left = newNode(4);
root->left->right = newNode(5);
root->right->left = newNode(6);
root->right->right = newNode(7);
root->right->left->right = newNode(8);
cout << "Sum of all elements in the binary tree is: "
<< sumBT(root);
}
//This code is contributed by Sarthak Delori
输出
Sum of all elements in the binary tree is: 36
时间复杂度:O(n)
辅助空间:O(n)