From 62f8bbf4690030966cee27084af56d00f9b3534e Mon Sep 17 00:00:00 2001
From: Ian C <ianc@noddybox.co.uk>
Date: Sun, 8 Jul 2018 17:01:55 +0000
Subject: Initial working version.

---
 codeword.c | 96 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 93 insertions(+), 3 deletions(-)

diff --git a/codeword.c b/codeword.c
index 7b215a9..7a87f51 100644
--- a/codeword.c
+++ b/codeword.c
@@ -2,6 +2,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <errno.h>
+#include <ctype.h>
 
 typedef struct
 {
@@ -10,14 +11,20 @@ typedef struct
     char letter;
 } Character;
 
-static void Chomp(char *p)
+static void PrepLine(char *p)
 {
     size_t l = strlen(p);
+    size_t f;
 
     while (l && p[l-1] == '\n')
     {
     	p[--l] = 0;
     }
+
+    for(f = 0; f < l; f++)
+    {
+    	p[f] = tolower((unsigned char)p[f]);
+    }
 }
 
 static void Error(const char *p)
@@ -26,6 +33,82 @@ static void Error(const char *p)
     exit(EXIT_FAILURE);
 }
 
+static int ContainsLetter(char c, const Character *chars, int no_chars)
+{
+    int f;
+
+    for(f=0; f < no_chars; f++)
+    {
+    	if (chars[f].is_letter && chars[f].letter == c)
+	{
+	    return 1;
+	}
+    }
+
+    return 0;
+}
+
+static int CheckLettersAndLength(const char *buff,
+				 const Character *chars,
+				 int no_chars)
+{
+    size_t l = strlen(buff);
+    int f;
+
+    if (l != no_chars)
+    {
+    	return 0;
+    }
+
+    for(f=0; f < no_chars; f++)
+    {
+    	if (chars[f].is_letter &&
+	    (chars[f].letter != buff[f]))
+	{
+	    return 0;
+	}
+    }
+
+    return 1;
+}
+
+static int CheckNumbers(const char *buff, const Character *chars, int no_chars)
+{
+    int f;
+    int n;
+    char code[27] = {0};
+
+    for(f = 0; f < no_chars; f++)
+    {
+    	if (!chars[f].is_letter)
+	{
+	    int i = chars[f].number - 1;
+
+	    if (ContainsLetter(buff[f], chars, no_chars))
+	    {
+	    	return 0;
+	    }
+
+	    if (code[i] && code[i] != buff[f])
+	    {
+	    	return 0;
+	    }
+
+	    for(n = 0; n < 27; n++)
+	    {
+	    	if (n != i && code[n] == buff[f])
+		{
+		    return 0;
+		}
+	    }
+
+	    code[i] = buff[f];
+	}
+    }
+
+    return 1;
+}
+
 int main(int argc, char *argv[])
 {
     int no_chars;
@@ -54,10 +137,10 @@ int main(int argc, char *argv[])
 
 	i = atoi(argv[f+2]);
 
-	if (i == 0)
+	if (i < 1 || i > 27)
 	{
 	    chars[f].is_letter = 1;
-	    chars[f].letter = argv[f+2][0];
+	    chars[f].letter = tolower((unsigned char)argv[f+2][0]);
 	    chars[f].number = 0;
 	}
 	else
@@ -77,6 +160,13 @@ int main(int argc, char *argv[])
 
     while(fgets(buff, sizeof buff, fp))
     {
+    	PrepLine(buff);
+
+	if (CheckLettersAndLength(buff, chars, no_chars) &&
+	    CheckNumbers(buff, chars, no_chars))
+	{
+	    printf("%s\n", buff);
+	}
     }
 
     return EXIT_SUCCESS;
-- 
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