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[code fix] Fixed trie_tree for code quality and docs & clang-tidy error check (#1059)
* attempt to fix trie-tree code * clang-tidy fixes * remove performance-unnecessary-value-param as error - this has auto-fix * make test() static * added original author to the description * added namespace * doc updates * fix true spelling * extended to small & big caps alphabets - 52 characters * clang-format and clang-tidy fixes for edc2247 * move const parameter to after the parameters Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
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‎.clang-tidy

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---
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Checks: '-*,google-*,clang-analyzer-*,-clang-analyzer-security.insecureAPI.*,cppcoreguidelines-*,-cppcoreguidelines-avoid-magic-numbers,-cppcoreguidelines-pro-bounds-*,openmp-*,performance-*,portability-*,modernize-*,-modernize-use-trailing-*'
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WarningsAsErrors: '*,-google-readability-*,-google-explicit-constructor,-modernize-*,modernize-avoid-c-arrays,-performance-move-const-arg,-performance-noexcept-move-constructor,-cppcoreguidelines-init-variables,-cppcoreguidelines-pro-*,-cppcoreguidelines-owning-memory,-clang-analyzer-cplusplus.Move'
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WarningsAsErrors: '*,-google-readability-*,-google-explicit-constructor,-modernize-*,modernize-avoid-c-arrays,-performance-move-const-arg,-performance-noexcept-move-constructor,-performance-unnecessary-value-param,-cppcoreguidelines-init-variables,-cppcoreguidelines-pro-*,-cppcoreguidelines-owning-memory,-clang-analyzer-cplusplus.Move'
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HeaderFilterRegex: ''
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AnalyzeTemporaryDtors: false
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FormatStyle: '{ BasedOnStyle: Google, UseTab: Never, IndentWidth: 4, TabWidth: 4, AllowShortIfStatementsOnASingleLine: false, IndentCaseLabels: true, ColumnLimit: 80, AccessModifierOffset: -3, AlignConsecutiveMacros: true }'

‎data_structures/trie_tree.cpp

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#include <stdbool.h>
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#include <stdio.h>
3-
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/**
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* @file
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* @author [@Arctic2333](https://github.com/Arctic2333)
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* @author [Krishna Vedala](https://github.com/kvedala)
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* @brief Implementation of [Trie](https://en.wikipedia.org/wiki/Trie) data
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* structure for English alphabets in small characters.
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* @note the function ::data_structure::trie::deleteString might be erroneous
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* @see trie_modern.cpp
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*/
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#include <array>
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#include <cassert>
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#include <iostream>
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#include <memory>
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#include <string>
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#include <vector>
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7-
// structure definition
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typedef struct trie {
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struct trie* arr[26];
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bool isEndofWord;
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} trie;
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// create a new node for trie
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trie* createNode() {
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trie* nn = new trie();
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for (int i = 0; i < 26; i++) nn->arr[i] = NULL;
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nn->isEndofWord = false;
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return nn;
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}
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/** \namespace data_structure
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* \brief Data-structure algorithms
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*/
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namespace data_structure {
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/**
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* @brief [Trie](https://en.wikipedia.org/wiki/Trie) implementation for
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* small-case English alphabets `a-z`
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*/
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class trie {
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private:
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static constexpr uint8_t NUM_CHARS = 26; ///< Number of alphabets
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/** @brief Recursive tree nodes as an array of shared-pointers */
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std::array<std::shared_ptr<trie>, NUM_CHARS << 1> arr;
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bool isEndofWord = false; ///< identifier if a node is terminal node
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21-
// insert string into the trie
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void insert(trie* root, std::string str) {
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for (int i = 0; i < str.length(); i++) {
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int j = str[i] - 'a';
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if (root->arr[j]) {
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root = root->arr[j];
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} else {
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root->arr[j] = createNode();
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root = root->arr[j];
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/**
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* @brief Convert a character to integer for indexing
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*
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* @param ch character to index
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* @return unsigned integer index
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*/
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uint8_t char_to_int(const char& ch) const {
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if (ch >= 'A' && ch <= 'Z') {
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return ch - 'A';
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} else if (ch >= 'a' && ch <= 'z') {
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return ch - 'a' + NUM_CHARS;
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}
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std::cerr << "Invalid character present. Exiting...";
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std::exit(EXIT_FAILURE);
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return 0;
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}
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root->isEndofWord = true;
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}
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// search a string exists inside the trie
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bool search(trie* root, std::string str, int index) {
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if (index == str.length()) {
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if (!root->isEndofWord)
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/** search a string exists inside a given root trie
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* @param str string to search for
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* @param index start index to search from
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* @returns `tre` if found
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* @returns `false` if not found
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*/
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bool search(const std::shared_ptr<trie>& root, const std::string& str,
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int index) {
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if (index == str.length()) {
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if (!root->isEndofWord) {
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return false;
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}
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return true;
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}
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int j = char_to_int(str[index]);
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if (!root->arr[j]) {
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return false;
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return true;
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}
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return search(root->arr[j], str, index + 1);
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}
42-
int j = str[index] - 'a';
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if (!root->arr[j])
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return false;
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return search(root->arr[j], str, index + 1);
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}
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/*
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removes the string if it is not a prefix of any other
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string, if it is then just sets the endofword to false, else
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removes the given string
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*/
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bool deleteString(trie* root, std::string str, int index) {
54-
if (index == str.length()) {
55-
if (!root->isEndofWord)
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return false;
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root->isEndofWord = false;
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for (int i = 0; i < 26; i++) return false;
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return true;
71+
public:
72+
trie() = default; ///< Class default constructor
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74+
/** insert string into the trie
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* @param str String to insert in the tree
76+
*/
77+
void insert(const std::string& str) {
78+
std::shared_ptr<trie> root(nullptr);
79+
80+
for (const char& ch : str) {
81+
int j = char_to_int(ch);
82+
if (root) {
83+
if (root->arr[j]) {
84+
root = root->arr[j];
85+
} else {
86+
std::shared_ptr<trie> temp(new trie());
87+
root->arr[j] = temp;
88+
root = temp;
89+
}
90+
} else if (arr[j]) {
91+
root = arr[j];
92+
} else {
93+
std::shared_ptr<trie> temp(new trie());
94+
arr[j] = temp;
95+
root = temp;
96+
}
97+
}
98+
root->isEndofWord = true;
6099
}
61-
int j = str[index] - 'a';
62-
if (!root->arr[j])
63-
return false;
64-
bool var = deleteString(root, str, index + 1);
65-
if (var) {
66-
root->arr[j] = NULL;
67-
if (root->isEndofWord) {
100+
101+
/** search a string exists inside the trie
102+
* @param str string to search for
103+
* @param index start index to search from
104+
* @returns `true` if found
105+
* @returns `false` if not found
106+
*/
107+
bool search(const std::string& str, int index) {
108+
if (index == str.length()) {
109+
if (!isEndofWord) {
110+
return false;
111+
}
112+
return true;
113+
}
114+
int j = char_to_int(str[index]);
115+
if (!arr[j]) {
68116
return false;
69-
} else {
70-
int i;
71-
for (i = 0; i < 26; i++)
72-
if (root->arr[i])
73-
return false;
117+
}
118+
return search(arr[j], str, index + 1);
119+
}
120+
121+
/**
122+
* removes the string if it is not a prefix of any other
123+
* string, if it is then just sets the ::data_structure::trie::isEndofWord
124+
* to false, else removes the given string
125+
* @note the function ::data_structure::trie::deleteString might be
126+
* erroneous
127+
* @todo review the function ::data_structure::trie::deleteString and the
128+
* commented lines
129+
* @param str string to remove
130+
* @param index index to remove from
131+
* @returns `true` if successful
132+
* @returns `false` if unsuccessful
133+
*/
134+
bool deleteString(const std::string& str, int index) {
135+
if (index == str.length()) {
136+
if (!isEndofWord) {
137+
return false;
138+
}
139+
isEndofWord = false;
140+
// following lines - possible source of error?
141+
// for (int i = 0; i < NUM_CHARS; i++)
142+
// if (!arr[i])
143+
// return false;
74144
return true;
75145
}
146+
int j = char_to_int(str[index]);
147+
if (!arr[j]) {
148+
return false;
149+
}
150+
bool var = deleteString(str, index + 1);
151+
if (var) {
152+
arr[j].reset();
153+
if (isEndofWord) {
154+
return false;
155+
} else {
156+
int i = 0;
157+
for (i = 0; i < NUM_CHARS; i++) {
158+
if (arr[i]) {
159+
return false;
160+
}
161+
}
162+
return true;
163+
}
164+
}
165+
166+
/* should not return here */
167+
std::cout << __func__ << ":" << __LINE__
168+
<< "Should not reach this line\n";
169+
return false;
76170
}
171+
};
172+
} // namespace data_structure
173+
174+
/**
175+
* @brief Testing function
176+
* @returns void
177+
*/
178+
static void test() {
179+
data_structure::trie root;
180+
root.insert("Hello");
181+
root.insert("World");
182+
183+
assert(!root.search("hello", 0));
184+
std::cout << "hello - " << root.search("hello", 0) << "\n";
185+
186+
assert(root.search("Hello", 0));
187+
std::cout << "Hello - " << root.search("Hello", 0) << "\n";
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78-
/* should not return here */
79-
std::cout << __func__ << ":" << __LINE__ << "Should not reach this line\n";
80-
return false;
189+
assert(!root.search("Word", 0));
190+
std::cout << "Word - " << root.search("Word", 0) << "\n";
191+
192+
assert(root.search("World", 0));
193+
std::cout << "World - " << root.search("World", 0) << "\n";
194+
195+
// Following lines of code give erroneous output
196+
// root.deleteString("hello", 0);
197+
// assert(!root.search("hello", 0));
198+
// std::cout << "hello - " << root.search("world", 0) << "\n";
81199
}
82200

201+
/**
202+
* @brief Main function
203+
* @return 0 on exit
204+
*/
83205
int main() {
84-
trie* root = createNode();
85-
insert(root, "hello");
86-
insert(root, "world");
87-
int a = search(root, "hello", 0);
88-
int b = search(root, "word", 0);
89-
printf("%d %d ", a, b);
206+
test();
207+
90208
return 0;
91209
}

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