write the //TODO part of the program: /*************************************************************************** * scramble.c * * Problem Set 3 * * Implements Scramble with CS50. …

write the //TODO part of the program: /*************************************************************************** * scramble.c * * Problem Set 3 * * Implements Scramble with CS50. * * Usage: scramble [#] * * where # is an optional grid number. ***************************************************************************/ #include [removed] #include [removed] #include [removed] #include [removed] #include [removed] #include [removed] // duration of a game in seconds #define DURATION 30 // grid’s dimensions #define DIMENSION 4 // maximum number of words in any dictionary #define WORDS 172806 // maximum number of letters in any word #define LETTERS 29 // default dictionary // http://www.becomeawordgameexpert.com/wordlists.htm #define DICTIONARY “words” // for logging FILE* log; // grid char grid[DIMENSION][DIMENSION]; // flags with which we can mark grid’s letters while searching for words bool marks[DIMENSION][DIMENSION]; // defines a word as having an array of letters plus a flag // indicating whether word has been found on grid typedef struct { bool found; char letters[LETTERS + 1]; } word; // defines a dictionary as having a size and an array of words struct { int size; word words[WORDS]; } dictionary; // prototypes void clear(void); bool crawl(string letters, int x, int y); void draw(void); bool find(string s); void initialize(void); bool load(string s); bool lookup(string s); void scramble(void); // This is Scramble. int main(int argc, string argv[]) { // ensure proper usage if (argc > 2) { printf(“Usage: %s [#]n”, basename(argv[0])); return 1; } // seed pseudorandom number generator if (argc == 2) { int seed = atoi(argv[1]); if (seed <= 0) { printf(“Invalid grid.n”); return 1; } srand(seed); } else srand(time(NULL)); // determine path to dictionary string directory = dirname(argv[0]); char path[strlen(directory) + 1 + strlen(DICTIONARY) + 1]; sprintf(path, “%s/%s”, directory, DICTIONARY); // load dictionary if (!load(path)) { printf(“Could not open dictionary.n”); return 1; } // initialize the grid initialize(); // initialize user’s score int score = 0; // calculate time of game’s end int end = time(NULL) + DURATION; // open log log = fopen(“log.txt”, “w”); if (log == NULL) { printf(“Could not open log.n”); return 1; } // accept words until timer expires while (true) { // clear the screen clear(); // draw the current state of the grid draw(); // log board for (int row = 0; row < DIMENSION; row++) { for (int col = 0; col [removed]= end) { printf(“?33[31m”); // red printf(“Time: %dnn”, 0); printf(“?33[39m”); // default break; } // report time remaining printf(“Time: %dnn”, end – now); // prompt for word printf(“> “); string s = GetString(); // quit playing if user hits ctrl-d if (s == NULL) break; // log word fprintf(log, “%sn”, s); // check whether to scramble grid if (strcmp(s, “SCRAMBLE”) == 0) scramble(); // or to look for word on grid and in dictionary else { if (find(s) && lookup(s)) score += strlen(s); } } // close log fclose(log); return 0; } /** * Clears screen. */ void clear() { printf(“?33[2J”); printf(“?33[%d;%dH”, 0, 0); } /** * Crawls grid recursively for letters starting at grid[x][y]. * Returns true iff all letters are found. */ bool crawl(string letters, int x, int y) { // if out of letters, then we must’ve found them all! if (strlen(letters) == 0) return true; // don’t fall off the grid! if (x [removed]= DIMENSION) return false; if (y [removed]= DIMENSION) return false; // been here before! if (marks[x][y]) return false; // check grid[x][y] for current letter if (grid[x][y] != letters[0]) return false; // mark location marks[x][y] = true; // look left and right for next letter for (int i = -1; i <= 1; i++) { // look down and up for next letter for (int j = -1; j <= 1; j++) { // check grid[x + i][y + j] for next letter if (crawl(&letters[1], x + i, y + j)) return true; } } // unmark location marks[x][y] = false; // fail return false; } /** * Prints the grid in its current state. */ void draw(void) { // TODO } /** * Returns true iff word, s, is found in grid. */ bool find(string s) { // word must be at least 2 characters in length if (strlen(s) < 2) return false; // search grid for word for (int row = 0; row < DIMENSION; row++) { for (int col = 0; col < DIMENSION; col++) { // reset marks for (int i = 0; i < DIMENSION; i++) for (int j = 0; j < DIMENSION; j++) marks[i][j] = false; // search for word starting at grid[i][j] if (crawl(s, row, col)) return true; } } return false; } /** * Initializes grid with letters. */ void initialize(void) { // http://en.wikipedia.org/wiki/Letter_frequency float frequencies[] = { 8.167, // a 1.492, // b 2.782, // c 4.253, // d 12.702, // e 2.228, // f 2.015, // g 6.094, // h 6.966, // i 0.153, // j 0.747, // k 4.025, // l 2.406, // m 6.749, // n 7.507, // o 1.929, // p 0.095, // q 5.987, // r 6.327, // s 9.056, // t 2.758, // u 1.037, // v 2.365, // w 0.150, // x 1.974, // y 0.074 // z }; int n = sizeof(frequencies) / sizeof(float); // iterate over grid for (int row = 0; row < DIMENSION; row++) { for (int col = 0; col < DIMENSION; col++) { // generate pseudorandom double in [0, 1] double d = rand() / (double) RAND_MAX; // map d onto range of frequencies for (int k = 0; k < n; k++) { d -= frequencies[k] / 100; if (d < 0.0 || k == n – 1) { grid[row][col] = ‘A’ + k; break; } } } } } /** * Loads words from dictionary with given filename, s, into a global array. */ bool load(string s) { // open dictionary FILE* file = fopen(s, “r”); if (file == NULL) return false; // initialize dictionary’s size dictionary.size = 0; // load words from dictionary char buffer[LETTERS + 2]; while (fgets(buffer, LETTERS + 2, file)) { // overwrite n with ? buffer[strlen(buffer) – 1] = ‘?’; // capitalize word for (int i = 0, n = strlen(buffer); i < n; i++) buffer[i] = toupper(buffer[i]); // ignore SCRAMBLE if (strcmp(buffer, “SCRAMBLE”) == 0) continue; // copy word into dictionary dictionary.words[dictionary.size].found = false; strncpy(dictionary.words[dictionary.size].letters, buffer, LETTERS + 1); dictionary.size++; } // success! return true; } /** * Looks up word, s, in dictionary. Iff found (for the first time), flags word * as found (so that user can’t score with it again) and returns true. */ bool lookup(string s) { // TODO return false; } /** * Scrambles the grid by rotating it 90 degrees clockwise, whereby * grid[0][0] rotates to grid[0][DIMENSION – 1]. */ void scramble(void) { // TODO }