Word Search

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

Author: begeekmyfriend

079_word_search/word_search.c

@@ -37,7 +37,8 @@ static bool dfs(char *word, char **board, bool *used,
     return result;
 }
 
-static bool exist(char** board, int boardRowSize, int boardColSize, char* word) {
+static bool exist(char** board, int boardRowSize, int boardColSize, char* word)
+{
     int i, j;
     int len = strlen(word);
     if (len > boardRowSize * boardColSize) {

212_word_search_ii/Makefile

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

212_word_search_ii/word_search.c

@@ -0,0 +1,196 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+
+struct trie {
+    struct trie *subs[27];
+    char letters[27];
+    int num;
+};
+
+static struct trie* trie_create()
+{
+    struct trie *obj = malloc(sizeof(*obj));
+    memset(obj->letters, 0xff, sizeof(obj->letters));
+    memset(&obj->subs[0], 0, sizeof(obj->subs));
+    obj->num = 0;
+    return obj;
+}
+
+static void trie_insert(struct trie* obj, char* word)
+{
+    while (*word != '\0') {
+        int pos = *word - 'a' + 1;
+        obj->letters[pos] = *word++;
+        obj->num++;
+        if (obj->subs[pos] == NULL) {
+            obj->subs[pos] = trie_create();
+        }
+        obj = obj->subs[pos];
+    }
+    obj->letters[0] = '\0';
+}
+
+static void trie_remove(struct trie* obj, char* word)
+{
+    while (obj != NULL && *word != '\0') {
+        int pos = *word++ - 'a' + 1;
+        if (--obj->num == 0) {
+            obj->letters[pos] = 0xff;
+        }
+        obj = obj->subs[pos];
+    }
+    if (obj != NULL) {
+        obj->letters[0] = 0xff;
+    }
+}
+
+static void dfs(char **board, int row_size, int col_size, int row, int col, struct trie *node,
+                char *word, int len, bool *used, char **results, int *count, struct trie *root, int *wordsSize)
+{
+    char c = board[row][col];
+    int index = c - 'a' + 1;
+
+    if (node == NULL || node->letters[index] == -1) {
+        return;
+    }
+
+    printf("%d %d\n", row, col);
+    word[len] = c;
+
+    struct trie *sub = node->subs[index];
+    if (sub != NULL && sub->letters[0] == '\0') {
+        word[len + 1] = '\0';
+        results[*count] = malloc(len + 2);
+        strcpy(results[*count], word);
+        (*count)++;
+        trie_remove(root, word);
+        (*wordsSize)--;
+        printf("%s\n", word);
+    }
+
+    used[row * col_size + col] = true;
+
+    if (row > 0 && !used[(row - 1) * col_size + col]) {
+        dfs(board, row_size, col_size, row - 1, col, node->subs[index], word, len + 1, used, results, count, root, wordsSize);
+    }
+
+    if (row < row_size - 1 && !used[(row + 1) * col_size + col]) {
+        dfs(board, row_size, col_size, row + 1, col, node->subs[index], word, len + 1, used, results, count, root, wordsSize);
+    }
+
+    if (col > 0 && !used[row * col_size + col - 1]) {
+        dfs(board, row_size, col_size, row, col - 1, node->subs[index], word, len + 1, used, results, count, root, wordsSize);
+    }
+
+    if (col < col_size - 1 && !used[row * col_size + col + 1]) {
+        dfs(board, row_size, col_size, row, col + 1, node->subs[index], word, len + 1, used, results, count, root, wordsSize);
+    }
+
+    used[row * col_size + col] = false;
+}
+
+/**
+ * Return an array of size *returnSize.
+ * Note: The returned array must be malloced, assume caller calls free().
+ */
+static char **findWords(char** board, int boardRowSize, int boardColSize, char** words, int wordsSize, int* returnSize)
+{
+    int i, j, cap = 5000;
+    struct trie *root = trie_create();
+    for (i = 0; i < wordsSize; i++) {
+        trie_insert(root, words[i]);
+    }
+
+    *returnSize = 0;
+    char *word = malloc(boardRowSize * boardColSize + 1);
+    memset(word, 0, boardRowSize * boardColSize + 1);
+    char **results = malloc(cap * sizeof(char *));
+    bool *used = malloc(boardRowSize * boardColSize);
+    memset(used, false, boardRowSize * boardColSize);
+    for (i = 0; i < boardRowSize; i++) {
+        for (j = 0; j < boardColSize; j++) {
+            if (wordsSize == 0) {
+                return results;
+            }
+            dfs(board, boardRowSize, boardColSize, i, j, root, word, 0, used, results, returnSize, root, &wordsSize);
+        }
+    }
+    return results;
+}
+
+int main(void)
+{
+    int i;
+#if 0
+    int row = 4;
+    int col = 4;
+    char **board = malloc(row * sizeof(char *));
+    board[0] = malloc(col);
+    board[0][0] = 'o';
+    board[0][1] = 'a';
+    board[0][2] = 'a';
+    board[0][3] = 'n';
+    board[1] = malloc(col);
+    board[1][0] = 'e';
+    board[1][1] = 't';
+    board[1][2] = 'a';
+    board[1][3] = 'e';
+    board[2] = malloc(col);
+    board[2][0] = 'i';
+    board[2][1] = 'h';
+    board[2][2] = 'k';
+    board[2][3] = 'r';
+    board[3] = malloc(col);
+    board[3][0] = 'i';
+    board[3][1] = 'f';
+    board[3][2] = 'l';
+    board[3][3] = 'v';
+
+    int size = 4;
+    char **words = malloc(size * sizeof(char *));
+    words[0] = malloc(5);
+    strcpy(words[0], "oath");
+    words[1] = malloc(5);
+    strcpy(words[1], "pea");
+    words[2] = malloc(5);
+    strcpy(words[2], "eat");
+    words[3] = malloc(5);
+    strcpy(words[3], "rain");
+#else
+    int row = 2;
+    int col = 2;
+    char **board = malloc(row * sizeof(char *));
+    board[0] = malloc(col);
+    board[0][0] = 'a';
+    board[0][1] = 'b';
+    board[1] = malloc(col);
+    board[1][0] = 'a';
+    board[1][1] = 'a';
+
+    int size = 7;
+    char **words = malloc(size * sizeof(char *));
+    words[0] = malloc(5);
+    words[1] = malloc(5);
+    words[2] = malloc(5);
+    words[3] = malloc(5);
+    words[4] = malloc(5);
+    words[5] = malloc(5);
+    words[6] = malloc(5);
+    strcpy(words[0], "aba");
+    strcpy(words[1], "baa");
+    strcpy(words[2], "bab");
+    strcpy(words[3], "aaab");
+    strcpy(words[4], "aaa");
+    strcpy(words[5], "aaaa");
+    strcpy(words[6], "aaba");
+#endif
+
+    int count = 0;
+    char **lists = findWords(board, row, col, words, size, &count);
+    for (i = 0; i < count; i++) {
+        printf("%s\n", lists[i]);
+    }
+    return 0;
+}