# 算法：在二叉搜索树中找到最小值的节点

2021年3月17日18:01:29 发表评论 345 次浏览

## C ++

``````//C++ program to find minimum value node in binary search Tree.
#include <bits/stdc++.h>
using namespace std;

/* A binary tree node has data, pointer to left child
and a pointer to right child */
struct node
{
int data;
struct node* left;
struct node* right;
};

/* Helper function that allocates a new node
with the given data and NULL left and right
pointers. */
struct node* newNode( int data)
{
struct node* node = ( struct node*)
malloc ( sizeof ( struct node));
node->data = data;
node->left = NULL;
node->right = NULL;

return (node);
}

/* Give a binary search tree and a number, inserts a new node with the given number in
the correct place in the tree. Returns the new
root pointer which the caller should then use
(the standard trick to avoid using reference
parameters). */
struct node* insert( struct node* node, int data)
{
/* 1. If the tree is empty, return a new, single node */
if (node == NULL)
return (newNode(data));
else
{
/* 2. Otherwise, recur down the tree */
if (data <= node->data)
node->left = insert(node->left, data);
else
node->right = insert(node->right, data);

/* return the (unchanged) node pointer */
return node;
}
}

/* Given a non-empty binary search tree, return the minimum data value found in that
tree. Note that the entire tree does not need
to be searched. */
int minValue( struct node* node)
{
struct node* current = node;

/* loop down to find the leftmost leaf */
while (current->left != NULL)
{
current = current->left;
}
return (current->data);
}

/* Driver Code*/
int main()
{
struct node* root = NULL;
root = insert(root, 4);
insert(root, 2);
insert(root, 1);
insert(root, 3);
insert(root, 6);
insert(root, 5);

cout << "\n Minimum value in BST is " << minValue(root);
getchar ();
return 0;
}

// This code is contributed by Mukul Singh.``````

## C

``````#include <stdio.h>
#include<stdlib.h>

/* A binary tree node has data, pointer to left child
and a pointer to right child */
struct node
{
int data;
struct node* left;
struct node* right;
};

/* Helper function that allocates a new node
with the given data and NULL left and right
pointers. */
struct node* newNode( int data)
{
struct node* node = ( struct node*)
malloc ( sizeof ( struct node));
node->data  = data;
node->left  = NULL;
node->right = NULL;

return (node);
}

/* Give a binary search tree and a number, inserts a new node with the given number in
the correct place in the tree. Returns the new
root pointer which the caller should then use
(the standard trick to avoid using reference
parameters). */
struct node* insert( struct node* node, int data)
{
/* 1. If the tree is empty, return a new, single node */
if (node == NULL)
return (newNode(data));
else
{
/* 2. Otherwise, recur down the tree */
if (data <= node->data)
node->left  = insert(node->left, data);
else
node->right = insert(node->right, data);

/* return the (unchanged) node pointer */
return node;
}
}

/* Given a non-empty binary search tree, return the minimum data value found in that
tree. Note that the entire tree does not need
to be searched. */
int minValue( struct node* node) {
struct node* current = node;

/* loop down to find the leftmost leaf */
while (current->left != NULL) {
current = current->left;
}
return (current->data);
}

/* Driver program to test sameTree function*/
int main()
{
struct node* root = NULL;
root = insert(root, 4);
insert(root, 2);
insert(root, 1);
insert(root, 3);
insert(root, 6);
insert(root, 5);

printf ( "\n Minimum value in BST is %d" , minValue(root));
getchar ();
return 0;
}``````

## Java

``````// Java program to find minimum value node in Binary Search Tree

// A binary tree node
class Node {

int data;
Node left, right;

Node( int d) {
data = d;
left = right = null ;
}
}

class BinaryTree {

/* Given a binary search tree and a number, inserts a new node with the given number in
the correct place in the tree. Returns the new
root pointer which the caller should then use
(the standard trick to avoid using reference
parameters). */
Node insert(Node node, int data) {

/* 1. If the tree is empty, return a new, single node */
if (node == null ) {
return ( new Node(data));
} else {

/* 2. Otherwise, recur down the tree */
if (data <= node.data) {
node.left = insert(node.left, data);
} else {
node.right = insert(node.right, data);
}

/* return the (unchanged) node pointer */
return node;
}
}

/* Given a non-empty binary search tree, return the minimum data value found in that
tree. Note that the entire tree does not need
to be searched. */
int minvalue(Node node) {
Node current = node;

/* loop down to find the leftmost leaf */
while (current.left != null ) {
current = current.left;
}
return (current.data);
}

// Driver program to test above functions
public static void main(String[] args) {
BinaryTree tree = new BinaryTree();
Node root = null ;
root = tree.insert(root, 4 );
tree.insert(root, 2 );
tree.insert(root, 1 );
tree.insert(root, 3 );
tree.insert(root, 6 );
tree.insert(root, 5 );

System.out.println( "Minimum value of BST is " + tree.minvalue(root));
}
}

// This code is contributed by Mayank Jaiswal``````

## python

``````# Python program to find the node with minimum value in bst

# A binary tree node
class Node:

# Constructor to create a new node
def __init__( self , key):
self .data = key
self .left = None
self .right = None

""" Give a binary search tree and a number, inserts a new node with the given number in
the correct place in the tree. Returns the new
root pointer which the caller should then use
(the standard trick to avoid using reference
parameters). """
def insert(node, data):

# 1. If the tree is empty, return a new, # single node
if node is None :
return (Node(data))

else :
# 2. Otherwise, recur down the tree
if data < = node.data:
node.left = insert(node.left, data)
else :
node.right = insert(node.right, data)

# Return the (unchanged) node pointer
return node

""" Given a non-empty binary search tree, return the minimum data value found in that
tree. Note that the entire tree does not need
to be searched. """
def minValue(node):
current = node

# loop down to find the lefmost leaf
while (current.left is not None ):
current = current.left

return current.data

# Driver program
root = None
root = insert(root, 4 )
insert(root, 2 )
insert(root, 1 )
insert(root, 3 )
insert(root, 6 )
insert(root, 5 )

print "\nMinimum value in BST is %d"  % (minValue(root))

# This code is contributed by Nikhil Kumar Singh(nickzuck_007)``````

## C#

``````using System;

// C# program to find minimum value node in Binary Search Tree

// A binary tree node
public class Node
{

public int data;
public Node left, right;

public Node( int d)
{
data = d;
left = right = null ;
}
}

public class BinaryTree
{

/* Given a binary search tree and a number, inserts a new node with the given number in
the correct place in the tree. Returns the new
root pointer which the caller should then use
(the standard trick to avoid using reference
parameters). */
public virtual Node insert(Node node, int data)
{

/* 1. If the tree is empty, return a new, single node */
if (node == null )
{
return ( new Node(data));
}
else
{

/* 2. Otherwise, recur down the tree */
if (data <= node.data)
{
node.left = insert(node.left, data);
}
else
{
node.right = insert(node.right, data);
}

/* return the (unchanged) node pointer */
return node;
}
}

/* Given a non-empty binary search tree, return the minimum data value found in that
tree. Note that the entire tree does not need
to be searched. */
public virtual int minvalue(Node node)
{
Node current = node;

/* loop down to find the leftmost leaf */
while (current.left != null )
{
current = current.left;
}
return (current.data);
}

// Driver program to test above functions
public static void Main( string [] args)
{
BinaryTree tree = new BinaryTree();
Node root = null ;
root = tree.insert(root, 4);
tree.insert(root, 2);
tree.insert(root, 1);
tree.insert(root, 3);
tree.insert(root, 6);
tree.insert(root, 5);

Console.WriteLine( "Minimum value of BST is " + tree.minvalue(root));
}
}

// This code is contributed by Shrikant13``````

## 的PHP

``````<?php
// PHP program to find the node with
// minimum value in bst

// create a binary tree
class node
{
private \$node , \$left , \$right ;
function __construct( \$node )
{
\$this ->node = \$node ;
\$left = \$right = NULL;
}

// set the left node in tree
function set_left( \$left )
{
\$this ->left = \$left ;
}

// set the right node in tree
function set_right( \$right )
{
\$this ->right = \$right ;
}

// get left node
function get_left()
{
return \$this ->left;
}

// get right node
function get_right()
{
return \$this ->right;
}

// get value of current node
function get_node()
{
return \$this ->node;
}

}

// Find the node with minimum value
// in a Binary Search Tree
function get_minimum_value( \$node )
{
/*travel till last left node to
get the minimum value*/
while ( \$node ->get_left() != NULL)
{
\$node = \$node ->get_left();
}
return \$node ->get_node();
}

// code to creating a tree
\$node = new node(4);
\$lnode = new node(2);
\$lnode ->set_left( new node(1));
\$lnode ->set_right( new node(3));
\$rnode = new node(6);
\$rnode ->set_left( new node(5));
\$node ->set_left( \$lnode );
\$node ->set_right( \$rnode );

\$minimum_value = get_minimum_value( \$node );
echo 'Minimum value of BST is ' .
\$minimum_value ;

// This code is contributed
// by Deepika Pathak
?>``````

``Minimum value in BST is 1``

O(n)最坏的情况发生在左偏斜的树上。

http://cslibrary.stanford.edu/110/BinaryTrees.html