Merge pull request neetcode-gh#2766 from mdmzfzl/leetcode-212

Added 212-word-search-ii.c

Author: mdmzfzl

c/212-word-search-ii.c

@@ -0,0 +1,87 @@
+typedef struct TrieNode trie_t;
+
+struct TrieNode {
+    bool valid;
+    char* word;
+    int count;
+    trie_t* parent;
+    trie_t* children[26];
+};
+
+void insert(trie_t* root, char* word) {
+    char* curr = word;
+    while (*curr != '\0') {
+        int index = *curr - 'a';
+        if (root->children[index] == NULL) {
+            root->children[index] = (trie_t*)calloc(1, sizeof(trie_t));
+            root->children[index]->valid = true;
+            root->children[index]->parent = root;
+        }
+        root->count++;
+        root = root->children[index];
+        curr++;
+    }
+    root->count++;
+    root->word = word;
+}
+
+void traverse(char** result, int* resultSize, char** board, bool** visited, int boardSize, int boardColSize, int x, int y, trie_t* node) {
+    if (node == NULL || !node->valid) {
+        return;
+    }
+    if (node->word != NULL) {
+        result[(*resultSize)++] = node->word;
+        node->word = NULL;
+        trie_t* curNode = node;
+        while (curNode != NULL) {
+            curNode->count--;
+            if (curNode->count <= 0) {
+                curNode->valid = false;
+            }
+            curNode = curNode->parent;
+        }
+    }
+    visited[x][y] = true;
+
+    int directions[4][2] = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};
+    for (int i = 0; i < 4; i++) {
+        int newX = x + directions[i][0];
+        int newY = y + directions[i][1];
+        if (newX >= 0 && newX < boardSize && newY >= 0 && newY < boardColSize && !visited[newX][newY]) {
+            int c = board[newX][newY] - 'a';
+            traverse(result, resultSize, board, visited, boardSize, boardColSize, newX, newY, node->children[c]);
+        }
+    }
+    
+    visited[x][y] = false;
+}
+
+char ** findWords(char** board, int boardSize, int* boardColSize, char ** words, int wordsSize, int* returnSize) {
+    // Create the trie and insert words
+    trie_t* trie = (trie_t*) calloc(1, sizeof(trie_t));
+    for (int i = 0; i < wordsSize; i++) {
+        insert(trie, words[i]);
+    }
+    
+    // Allocate memory for the result array
+    char** result = (char**) malloc(sizeof(char*) * wordsSize);
+    int resultSize = 0;
+    
+    // Create and initialize the visited array
+    bool** visited = (bool**) malloc(sizeof(bool*) * boardSize);
+    for (int i = 0; i < boardSize; i++) {
+        visited[i] = (bool*) calloc(*boardColSize, sizeof(bool));
+    }
+    
+    // Traverse the board and find words
+    for (int i = 0; i < boardSize; i++) {
+        for (int j = 0; j < *boardColSize; j++) {
+            int c = board[i][j] - 'a';
+            traverse(result, &resultSize, board, visited, boardSize, *boardColSize, i, j, trie->children[c]);
+        }
+    }
+    
+    // Clean up and set the return size
+    *returnSize = resultSize;
+    return result;
+}