题目：

题解：

int directions[4][2] = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};bool check(char** board, int boardSize, int boardColSize, int** visited, int i, int j, char* s, int sSize, int k) {if (board[i][j] != s[k]) {return false;} else if (k == sSize - 1) {return true;}visited[i][j] = true;bool result = false;for (int sel = 0; sel < 4; sel++) {int newi = i + directions[sel][0], newj = j + directions[sel][1];if (newi >= 0 && newi < boardSize && newj >= 0 && newj < boardColSize) {if (!visited[newi][newj]) {bool flag = check(board, boardSize, boardColSize, visited, newi, newj, s, sSize, k + 1);if (flag) {result = true;break;}}}}visited[i][j] = false;return result;
}bool exist(char** board, int boardSize, int* boardColSize, char* word) {int** visited = malloc(sizeof(int*) * boardSize);for (int i = 0; i < boardSize; i++) {visited[i] = malloc(sizeof(int) * boardColSize[0]);memset(visited[i], 0, sizeof(int) * boardColSize[0]);}int wordSize = strlen(word);for (int i = 0; i < boardSize; i++) {for (int j = 0; j < boardColSize[0]; j++) {bool flag = check(board, boardSize, boardColSize[0], visited, i, j, word, wordSize, 0);if (flag) {return true;}}}return false;
}