C solution for week 4, part 2

1 files changed, 146 insertions, 0 deletions

diff --git a/challenge-004/abigail/c/ch-2.c b/challenge-004/abigail/c/ch-2.c
new file mode 100644
index 0000000000..3df60fc2dc
--- /dev/null
+++ b/challenge-004/abigail/c/ch-2.c
@@ -0,0 +1,146 @@
+# include <stdlib.h>
+# include <stdio.h>
+# include <string.h>
+# include <unistd.h>
+# include <limits.h>
+# include <ctype.h>
+# include <stdbool.h>
+
+# define NR_OF_LETTERS 26
+
+/*
+ * See ../README.md
+ */
+
+/*
+ * Run as: cc -o ch-2.o ch-2.c; ./ch-2.o -f FILE < input-file
+ */
+
+
+/*
+ * Helper method to allocate memory for a string.
+ */
+char * malloc_char (size_t size) {
+    char * string = (char *) malloc (size * sizeof (char));
+    if (string == NULL) {
+        perror (NULL);
+        exit (1);
+    }
+    return (string);
+}
+
+
+/*
+ * Given a bag of letters, and a file name, print out
+ * all the words in the file which can be made with the letters
+ */
+void extract_words (char * file_name, size_t letter_bag [NR_OF_LETTERS]) {
+    FILE * fh;
+    char *  word = NULL;
+    size_t  len  = 0;
+    size_t  str_len;
+    /*
+     * Open the file
+     */
+    if ((fh = fopen (file_name, "r")) == NULL) {
+        perror (NULL);
+        exit (1);
+    }
+
+    /*
+     * Iterate over the file, one word at a time.
+     */
+    while ((str_len = getline (&word, &len, fh)) != -1) {
+        bool   winner = true;
+        size_t word_bag [NR_OF_LETTERS];  /* Count letters in each word */
+
+        /*
+         * Initialize the bag
+         */
+        for (size_t i = 0; i < NR_OF_LETTERS; i ++) {
+            word_bag [i] = 0;
+        }
+
+        /*
+         * Iterate over the characters of the word (case insensitively),
+         * and count how often they occur. If for a character, we need
+         * more than there are in the letter bag, we cannot form the word.
+         */
+        for (size_t i = 0; i < str_len && winner; i ++) {
+            ssize_t index = islower (word [i]) ? word [i] - 'a'
+                          : isupper (word [i]) ? word [i] - 'A'
+                          : -1;
+            /*
+             * Set winner to false if we don't have enough letters.
+             */
+            winner = winner && (index < 0 ||
+                                ++ word_bag [index] <= letter_bag [index]);
+        }
+        if (winner) {
+            printf ("%s", word);
+        }
+    }
+
+    /*
+     * Close the file
+     */
+    if (fclose (fh)) {
+        perror (NULL);
+        exit (1);
+    }
+
+    free (word);
+
+    return;
+}
+
+int main (int argc, char ** argv) {
+    char *  letters = NULL;
+    size_t  len     = 0;
+    size_t  str_len;
+
+    int     ch;
+    char *  file_name = NULL;
+
+    /*
+     * Parse the command line
+     */
+    while ((ch = getopt (argc, argv, "f:")) != -1) {
+        switch (ch) {
+            case 'f':
+                file_name = malloc_char (PATH_MAX);
+                stpncpy (file_name, optarg, PATH_MAX);
+                break;
+        }
+    }
+    if (file_name == NULL) {
+        fprintf (stderr, "Requires a -f FILE parameter\n");
+        exit (1);
+    }
+
+    /*
+     * Read lines of input; each line is a letter set.
+     * Iterate over the letters, and count them, ingoring case.
+     * Then call method to extract the right words
+     */
+    while ((str_len = getline (&letters, &len, stdin)) != -1) {
+        size_t letter_bag [NR_OF_LETTERS];
+        for (size_t i = 0; i < NR_OF_LETTERS; i ++) {
+            letter_bag [i] = 0;
+        }
+        for (size_t i = 0; i < str_len; i ++) {
+            if (islower (letters [i])) {
+                letter_bag [letters [i] - 'a'] ++;
+            }
+            if (isupper (letters [i])) {
+                letter_bag [letters [i] - 'A'] ++;
+            }
+        }
+        extract_words (file_name, letter_bag);
+    }
+
+    free (letters);
+    free (file_name);
+
+    return (0);
+}