Implement trie

Signed-off-by: begeekmyfriend <begeekmyfriend@gmail.com>

Author: begeekmyfriend

208_implement_trie/Makefile

@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test trie.c

208_implement_trie/trie.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+
+typedef struct Trie {
+    struct Trie *subs[27];
+    char letters[27];
+} Trie;
+
+/** Initialize your data structure here. */
+static Trie* trieCreate()
+{
+    Trie *obj = malloc(sizeof(*obj));
+    memset(obj->letters, 0xff, sizeof(obj->letters));
+    memset(&obj->subs[0], 0, sizeof(obj->subs));
+    return obj;
+}
+
+/** Inserts a word into the trie. */
+static void trieInsert(Trie* obj, char* word)
+{
+    while (*word != '\0') {
+        int pos = *word - 'a' + 1;
+        obj->letters[pos] = *word++;
+        if (obj->subs[pos] == NULL) {
+            obj->subs[pos] = trieCreate();
+        }
+        obj = obj->subs[pos];
+    }
+    obj->letters[0] = '\0';
+}
+
+/** Returns if the word is in the trie. */
+static bool trieSearch(Trie* obj, char* word)
+{
+    while (obj != NULL) {
+        int pos = *word == '\0' ? 0 : *word - 'a' + 1;
+        if (obj->letters[pos] != *word) {
+            return false;
+        }
+        word++;
+        obj = obj->subs[pos];
+    }
+    return true;
+}
+
+/** Returns if there is any word in the trie that starts with the given prefix. */
+static bool trieStartsWith(Trie* obj, char* prefix)
+{
+    while (*prefix != '\0') {
+        int pos = *prefix - 'a' + 1;
+        if (pos < 0 || obj->letters[pos] != *prefix) {
+            return false;
+        }
+        if (*++prefix != '\0') {
+            if (obj->subs[pos] == NULL) {
+                return false;
+            }
+            obj = obj->subs[pos];
+        }
+    }
+    return true;
+}
+
+static void trieFree(Trie* obj)
+{
+    int i;
+    for (i = 0; i < sizeof(obj->letters); i++) {
+        if (obj->subs[i] != NULL) {
+            trieFree(obj->subs[i]);
+        }
+    }
+    free(obj);
+}
+
+int main(void)
+{
+    char *word1 = "abc";
+    char *word2 = "ab";
+
+    Trie* obj = trieCreate();
+    trieInsert(obj, word1);
+    printf("%s\n", trieSearch(obj, word1) ? "true" : "false");
+    printf("%s\n", trieSearch(obj, word2) ? "true" : "false");
+    trieInsert(obj, word2);
+    printf("%s\n", trieSearch(obj, word2) ? "true" : "false");
+    trieInsert(obj, word2);
+    printf("%s\n", trieStartsWith(obj, word2) ? "true" : "false");
+    trieFree(obj);
+    return 0;
+}

211_add_and_search_word/Makefile

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+all:
+	gcc -O2 -o test word_dict.c

211_add_and_search_word/word_dict.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+
+typedef struct WordDictionary {
+    struct WordDictionary *subs[27];
+    char letters[27];
+} WordDictionary;
+
+/** Initialize your data structure here. */
+static WordDictionary* wordDictionaryCreate()
+{
+    WordDictionary *obj = malloc(sizeof(*obj));
+    memset(obj->letters, 0xff, sizeof(obj->letters));
+    memset(&obj->subs[0], 0, sizeof(obj->subs));
+    return obj;
+}
+
+/** Inserts a word into the wordDictionary. */
+static void wordDictionaryInsert(WordDictionary* obj, char* word)
+{
+    while (*word != '\0') {
+        int pos = *word - 'a' + 1;
+        obj->letters[pos] = *word++;
+        if (obj->subs[pos] == NULL) {
+            obj->subs[pos] = wordDictionaryCreate();
+        }
+        obj = obj->subs[pos];
+    }
+    obj->letters[0] = '\0';
+}
+
+/** Returns if the word is in the wordDictionary. */
+static bool wordDictionarySearch(WordDictionary* obj, char* word)
+{
+    int i;
+    while (obj != NULL) {
+        if (*word == '.') {
+            bool found;
+            for (i = 1; i < sizeof(obj->letters); i++) {
+                if (obj->subs[i] != NULL) {
+                    found = wordDictionarySearch(obj->subs[i], word + 1);
+                    if (found) {
+                        return true;
+                    }
+                }
+            }
+            return false;
+        } else {
+            int pos = *word == '\0' ? 0 : *word - 'a' + 1;
+            if (obj->letters[pos] != *word) {
+                return false;
+            }
+            word++;
+            obj = obj->subs[pos];
+        }
+    }
+    return true;
+}
+
+static void wordDictionaryFree(WordDictionary* obj)
+{
+    int i;
+    for (i = 0; i < sizeof(obj->letters); i++) {
+        if (obj->subs[i] != NULL) {
+            wordDictionaryFree(obj->subs[i]);
+        }
+    }
+    free(obj);
+}
+
+int main(void)
+{
+    char *word1 = "abc";
+    char *word2 = "ab";
+    char *word3 = "...";
+
+    WordDictionary* obj = wordDictionaryCreate();
+    wordDictionaryInsert(obj, word1);
+    printf("%s\n", wordDictionarySearch(obj, word1) ? "true" : "false");
+    printf("%s\n", wordDictionarySearch(obj, word2) ? "true" : "false");
+    wordDictionaryInsert(obj, word2);
+    printf("%s\n", wordDictionarySearch(obj, word2) ? "true" : "false");
+    wordDictionaryInsert(obj, word2);
+    printf("%s\n", wordDictionarySearch(obj, word3) ? "true" : "false");
+    wordDictionaryFree(obj);
+    return 0;
+}