Trie是一种有效的信息检索数据结构。使用Trie，可以使搜索复杂度达到最佳极限。
给定一个字符串数组。任务是使用Trie以反向字典顺序打印所有字符串。如果输入数组中有重复项，则只需要打印一次即可。
例子：
Input: str = {"cat", "there", "caller", "their", "calling"}
Output: there
their
cat
calling
caller
root
/ \
c t
| |
a h
| \ |
l t e
| | \
l i r
| \ | |
e i r e
| |
r n
|
g
Input: str = {"Candy", "cat", "Caller", "calling"}
Output: cat
candy
calling
caller
root
|
c
|
a
/ | \
l n t
| |
l d
| \ |
e i y
| |
r n
|
g方法：
为了解决上述问题，首先，使用的所有字符串然后打印从上到下最右边的子树的一个字符串然后打印从上到下第二右子树的字符串然后打印第三右子树等构建Trie树。它类似于从右到左遍历树的顺序。
下面是上述方法的实现：
CPP
// C++ programm to print array of string
// in reverse dictionary order using trie
#include
using namespace std;
#define CHILDREN 26
#define MAX 100
// Trie node
struct trie {
trie* child[CHILDREN];
// endOfWord is true
// if the node represents
// end of a word
bool endOfWord;
};
// Function will return
// the new node initialized NULL
trie* createNode()
{
trie* temp = new trie();
temp->endOfWord = false;
for (int i = 0; i < CHILDREN; i++) {
// Initialize null to the all child
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 content of trie
void displayContent(trie* root, char str[], int level)
{
// If node is leaf node, it indicates end
// of string, so a null character is added
// and string is displayed
if (isLeafNode(root)) {
// Assign a null character in temporary string
str[level] = '\0';
cout << str << endl;
}
for (int i = CHILDREN - 1; i >= 0; i--) {
// check if NON NULL child is found
// add parent key to str and
// call the display function recursively
// for child node
if (root->child[i]) {
str[level] = i + 'a';
displayContent(root->child[i], str, level + 1);
}
}
}
// Function call for displaying content
void display(trie* itr)
{
int level = 0;
char str[MAX];
displayContent(itr, str, level);
}
// Driver code
int main()
{
trie* root = createNode();
insert(root, "their");
insert(root, "there");
insert(root, "answer");
insert(root, "any");
/* After inserting strings, trie will look like
root
/ \
a t
| |
n h
| \ |
s y e
| | \
w i r
| | |
e r e
|
r
*/
display(root);
return 0;
} Python3
# Python3 programm to print array of string
# in reverse dictionary order using trie
CHILDREN = 26
MAX = 100
# Trie node
class trie:
def __init__(self):
self.child = [0 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 NONE
def createNode():
temp = trie();
temp.endOfWord = False;
for i in range(CHILDREN):
# Initialize null to the all child
temp.child[i] = None;
return temp;
# Function will insert 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 content of trie
def displayContent(root, str, level):
# If node is leaf node, it indicates end
# of string, so a null character is added
# and string is displayed
if (isLeafNode(root)):
# Assign a null character in temporary string
print("".join(str[:level]))
for i in range(CHILDREN-1, -1, -1):
# check if NON NONE child is found
# add parent key to str and
# call the display function recursively
# for child node
if (root.child[i]):
str[level] = chr(i + ord('a'));
displayContent(root.child[i], str, level + 1);
# Function call for displaying content
def display(itr):
level = 0;
str = ['' for i in range(MAX)];
displayContent(itr, str, level);
# Driver code
if __name__=='__main__':
root = createNode();
insert(root, "their");
insert(root, "there");
insert(root, "answer");
insert(root, "any");
''' After inserting strings, trie will look like
root
/ \
a t
| |
n h
| \ |
s y e
| | \
w i r
| | |
e r e
|
r
'''
display(root);
# This code is contributed by rutvik_56输出：
there
their
any
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