给定一组字符串str ，任务是打印由给定字符串集构造的 Trie 的所有关节。
Joints of a Trie is the nodes in a trie that have more than one child.
例子：
Input:
str = {"cat", "there", "caller",
"their", "calling"}
Output: l, a, e
Explanation:
root
/ \
c t
| |
a h
/ | |
t l e
| | \
l i r
| \ | |
e i r e
| |
r n
|
g
Input:
str = {"Candy", "cat",
"Caller", "calling"}
Output: l, a
Explanation:
root
|
c
|
a
/ | \
l n t
| |
l d
| \ |
e i y
| |
r n
|
g方法：
请按照以下步骤解决问题：
- 遍历 Trie，并取一个currChild变量为零。
- 将currChild增加 1，当当前节点有子节点并且从当前节点返回时检查currChild是否大于 1。如果是，请打印此字符或关节。否则，跳到下一个字符。
下面是上述方法的实现：
C++
// C++ program to print all the
// joints of a Trie constructed
// from a given set of strings
#include
using namespace std;
#define CHILDREN 26
#define MAX 100
// Trie node
struct trie {
trie* child[CHILDREN];
bool endOfWord;
};
// Function will return the
// new node(initialized to NULLs)
trie* createNode()
{
trie* temp = new trie();
temp->endOfWord = false;
for (int i = 0; i < CHILDREN; i++) {
temp->child[i] = NULL;
}
return temp;
}
// Function will insert the
// string in a trie recursively
void insertRecursively(trie* itr,
string str, int i)
{
if (i < str.length()) {
int index = str[i] - 'a';
if (itr->child[index] == NULL) {
// Create a new node
itr->child[index] = createNode();
}
// Recursive call for insertion
// of string
insertRecursively(itr->child[index],
str, i + 1);
}
else {
// Make the endOfWord true
// which represents
// the end of string
itr->endOfWord = true;
}
}
// Function call to insert a string
void insert(trie* itr, string str)
{
// Function call with
// necessary arguments
insertRecursively(itr, str, 0);
}
// Function to check whether the
// node is leaf or not
bool isLeafNode(trie* root)
{
return root->endOfWord != false;
}
// Function to display the Joints of trie
void display(trie* root, trie* itr,
char str[], int level)
{
// Count current child
int currChild = 0;
for (int i = 0; i < CHILDREN; i++)
{
// Check for NON NULL child is found
// add parent key to str and
// call the display function
// recursively for child node
if (itr->child[i]) {
str[level] = i + 'a';
display(root, itr->child[i],
str, level + 1);
currChild++;
}
}
// Print character if it has more
// than 1 child
if (currChild > 1 && itr != root) {
cout << str[level - 1] << endl;
}
}
// Function call for displaying Joint
void displayJoint(trie* root)
{
int level = 0;
char str[MAX];
display(root, root, str, level);
}
// Driver code
int main()
{
trie* root = createNode();
vector s = { "geek", "geeky",
"geeks", "gel" };
for (string str : s) {
insert(root, str);
}
displayJoint(root);
return 0;
} Java
// Java program to print all the
// joints of a Trie constructed
// from a given set of Strings
import java.util.*;
class GFG{
static final int CHILDREN = 26;
static final int MAX = 100;
// Trie node
static class trie
{
trie []child = new trie[CHILDREN];
boolean endOfWord;
};
// Function will return the
// new node(initialized to nulls)
static trie createNode()
{
trie temp = new trie();
temp.endOfWord = false;
for (int i = 0; i < CHILDREN; i++)
{
temp.child[i] = null;
}
return temp;
}
// Function will insert the
// String in a trie recursively
static void insertRecursively(trie itr,
String str, int i)
{
if (i < str.length())
{
int index = str.charAt(i) - 'a';
if (itr.child[index] == null)
{
// Create a new node
itr.child[index] = createNode();
}
// Recursive call for insertion
// of String
insertRecursively(itr.child[index],
str, i + 1);
}
else
{
// Make the endOfWord true
// which represents
// the end of String
itr.endOfWord = true;
}
}
// Function call to insert a String
static void insert(trie itr, String str)
{
// Function call with
// necessary arguments
insertRecursively(itr, str, 0);
}
// Function to check whether the
// node is leaf or not
static boolean isLeafNode(trie root)
{
return root.endOfWord != false;
}
// Function to display the Joints of trie
static void display(trie root, trie itr,
char str[], int level)
{
// Count current child
int currChild = 0;
for (int i = 0; i < CHILDREN; i++)
{
// Check for NON null child is found
// add parent key to str and
// call the display function
// recursively for child node
if (itr.child[i] != null)
{
str[level] = (char) (i + 'a');
display(root, itr.child[i],
str, level + 1);
currChild++;
}
}
// Print character if it has more
// than 1 child
if (currChild > 1 && itr != root)
{
System.out.print(str[level - 1] + "\n");
}
}
// Function call for displaying Joint
static void displayJoint(trie root)
{
int level = 0;
char []str = new char[MAX];
display(root, root, str, level);
}
// Driver code
public static void main(String[] args)
{
trie root = createNode();
String []s = { "geek", "geeky",
"geeks", "gel" };
for (String str : s)
{
insert(root, str);
}
displayJoint(root);
}
}
// This code is contributed by sapnasingh4991Python3
# Python3 program to traverse in bottom up manner
CHILDREN = 26
MAX = 100
# Trie node
class trie:
def __init__(self):
self.child = [None for i in range(CHILDREN)]
# endOfWord is true if the node represents
# end of a word
self.endOfWord = False
# Function will return the new node(initialized to NULLs)
def createNode():
temp = trie()
return temp
# Function will inert the string in a trie recursively
def insertRecursively(itr, str, i):
if(i < len(str)):
index = ord(str[i]) - ord('a')
if(itr.child[index] == None ):
#Create a new node
itr.child[index] = createNode();
# Recursive call for insertion of string
insertRecursively(itr.child[index], str, i + 1);
else:
# Make the endOfWord true which represents
# the end of string
itr.endOfWord = True;
# Function call to insert a string
def insert(itr, str):
# Function call with necessary arguments
insertRecursively(itr, str, 0);
# Function to check whether the node is leaf or not
def isLeafNode(root):
return root.endOfWord != False;
# Function to display the Joints of trie
def display(root, itr, str, level):
# Count current child
currChild = 0;
for i in range(CHILDREN):
# Check for NON NULL child is found
# add parent key to str and
# call the display function
# recursively for child node
if (itr.child[i]):
str[level] = chr(i + ord('a'));
display(root, itr.child[i],str, level + 1);
currChild += 1
# Print character if it has more
# than 1 child
if (currChild > 1 and itr != root):
print(str[level - 1])
# Function call for displaying Joint
def displayJoint(root):
level = 0;
str = ['' for i in range(MAX)];
display(root, root, str, level);
# Driver code
if __name__=='__main__':
root = createNode()
s = ["geek", "geeky", "geeks", "gel"]
for str in s:
insert(root, str);
displayJoint(root)
# This code is contributed by rutvik_56C#
// C# program to print all the
// joints of a Trie constructed
// from a given set of Strings
using System;
class GFG{
static readonly int CHILDREN = 26;
static readonly int MAX = 100;
// Trie node
class trie
{
public trie []child = new trie[CHILDREN];
public bool endOfWord;
};
// Function will return the
// new node(initialized to nulls)
static trie createNode()
{
trie temp = new trie();
temp.endOfWord = false;
for(int i = 0; i < CHILDREN; i++)
{
temp.child[i] = null;
}
return temp;
}
// Function will insert the
// String in a trie recursively
static void insertRecursively(trie itr,
String str, int i)
{
if (i < str.Length)
{
int index = str[i] - 'a';
if (itr.child[index] == null)
{
// Create a new node
itr.child[index] = createNode();
}
// Recursive call for insertion
// of String
insertRecursively(itr.child[index],
str, i + 1);
}
else
{
// Make the endOfWord true
// which represents
// the end of String
itr.endOfWord = true;
}
}
// Function call to insert a String
static void insert(trie itr, String str)
{
// Function call with
// necessary arguments
insertRecursively(itr, str, 0);
}
// Function to check whether the
// node is leaf or not
static bool isLeafNode(trie root)
{
return root.endOfWord != false;
}
// Function to display the Joints of trie
static void display(trie root, trie itr,
char []str, int level)
{
// Count current child
int currChild = 0;
for(int i = 0; i < CHILDREN; i++)
{
// Check for NON null child is found
// add parent key to str and
// call the display function
// recursively for child node
if (itr.child[i] != null)
{
str[level] = (char)(i + 'a');
display(root, itr.child[i],
str, level + 1);
currChild++;
}
}
// Print character if it has more
// than 1 child
if (currChild > 1 && itr != root)
{
Console.Write(str[level - 1] + "\n");
}
}
// Function call for displaying Joint
static void displayJoint(trie root)
{
int level = 0;
char []str = new char[MAX];
display(root, root, str, level);
}
// Driver code
public static void Main(String[] args)
{
trie root = createNode();
String []s = { "geek", "geeky",
"geeks", "gel" };
foreach(String str in s)
{
insert(root, str);
}
displayJoint(root);
}
}
// This code is contributed by Rajput-Ji输出：
k
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