the code

Signed-off-by: Mattias Andrée <maandree@member.fsf.org>

1 files changed, 171 insertions, 0 deletions

diff --git a/src/learn-your-telephone-number.c b/src/learn-your-telephone-number.c
new file mode 100644
index 0000000..9c9f785
--- /dev/null
+++ b/src/learn-your-telephone-number.c
@@ -0,0 +1,171 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <alloca.h>
+#include <errno.h>
+#include <string.h>
+
+
+#define t(...)  do { if (__VA_ARGS__) goto fail; } while (0)
+
+
+static const char* argv0;
+
+
+char* compare(const char* restrict e, const char* restrict c)
+{
+  size_t en = strlen(e);
+  size_t cn = strlen(c);
+  size_t** matrix = alloca((en + 1) * sizeof(size_t*));
+  char** path_matrix = alloca((en + 1) * sizeof(char*));
+  size_t ei, ci, ri = 0;
+  char* rc = NULL;
+  
+  for (ei = 0; ei <= en; ei++)
+    {
+      matrix[ei] = alloca((cn + 1) * sizeof(size_t));
+      matrix[ei][0] = ei;
+      path_matrix[ei] = alloca((cn + 1) * sizeof(char));
+      path_matrix[ei][0] = '|';
+    }
+  for (ci = 0; ci <= cn; ci++)
+    {
+      matrix[0][ci] = ci;
+      path_matrix[0][ci] = '-';
+    }
+  path_matrix[0][0] = '\0';
+  
+  e--, c--;
+  
+  for (ei = 1; ei <= en; ei++)
+    for (ci = 1; ci <= cn; ci++)
+      {
+	size_t d = matrix[ei - 1][ci - 1];
+	size_t l = matrix[ei + 0][ci - 1];
+	size_t u = matrix[ei - 1][ci + 0];
+	size_t lu = 1 + (l < u ? l : u);
+	int ch = (e[ei] != c[ci]);
+	d += (size_t)ch;
+	matrix[ei][ci] = d < lu ? d : lu;
+	path_matrix[ei][ci] = d < lu ? (ch ? '\\' : '=') : (l < u ? '-' : '|');
+      }
+  
+  t (!(rc = malloc((en + cn + 2) * sizeof(char))));
+  
+#if 0
+  for (ei = 0; ei <= en; ei++)
+    {
+      for (ci = 0; ci <= cn; ci++)
+	printf("%zu%s", matrix[ei][ci], ci == cn ? "" :
+	                                path_matrix[ei][ci + 1] == '-' ? "\033[1;32m-\033[m" : " ");
+      printf("\n");
+      if (ei < en)
+	for (ci = 0; ci < cn; ci++)
+	  printf("%s%s", path_matrix[ei + 1][ci + 0] == '|' ? "\033[1;31m|\033[m" : " ",
+			 path_matrix[ei + 1][ci + 1] == '\\' ? "\033[1;33m\\\033[m" :
+			 path_matrix[ei + 1][ci + 1] == '=' ? "\033[1;39m\\\033[m" : " ");
+      printf("\n");
+    }
+#endif
+  
+  rc[ri++] = '\0';
+  for (ei = en, ci = cn; ei + ci;)
+    switch (path_matrix[ei][ci])
+      {
+      case '=':   ei--, ci--;  rc[ri++] = '=';  break;
+      case '\\':  ei--, ci--;  rc[ri++] = '!';  break;
+      case '|':   ei--;        rc[ri++] = '-';  break;
+      case '-':         ci--;  rc[ri++] = '+';  break;
+      default:
+	abort();
+      }
+  rc[ri] = '\0';
+  
+ fail:
+  return rc;
+}
+
+
+int main(int argc, char* argv[])
+{
+  char* correct;
+  char* entered = NULL;
+  size_t n = 0;
+  void* new;
+  char* w;
+  char* r;
+  char* path = NULL;
+  char* path_;
+  char* p;
+  int rc = 0;
+  
+  argv0 = argc ? argv[0] : "learn-your-telephone-number";
+  if (argc != 2)
+    goto usage;
+  
+  correct = alloca((2 * strlen(argv[1]) + 1) * sizeof(char));
+  for (w = correct, r = argv[1]; *r; r++)
+    if      (isdigit(*r))  *w++ = *r;
+    else if (isalpha(*r))  goto usage;
+    else if (*r == '+')    *w++ = '0', *w++ = '0';
+  *w = '\0';
+  
+  t (fprintf(stdout, "Enter your telephone number: ") < 0);
+  t (fflush(stdout));
+  t (errno = 0, getline(&entered, &n, stdin) < 0);
+  n = strlen(entered) - 1;
+  entered[n] = '\0';
+  
+  t (!(new = realloc(entered, (2 * n + 1) * sizeof(char))));
+  entered = new;
+  memmove(r = (entered + n), w = (entered), n + 1);
+  for (; *r; r++)
+    if      (isdigit(*r))  *w++ = *r;
+    else if (*r == '+')    *w++ = '0', *w++ = '0';
+  *w = '\0';
+  
+  if (!strcmp(entered, correct))
+    goto done;
+  t (!(path = compare(entered, correct)));
+  
+  path_ = strchr(path + 1, '\0');
+  t (fprintf(stdout, "\033[A\033[KEntered: ") < 0);
+  for (p = entered; *--path_;)
+    switch (*path_)
+      {
+      case '=':  t (fprintf(stdout, "\033[39m%c", *p++) < 0);  break;
+      case '!':  t (fprintf(stdout, "\033[31m%c", *p++) < 0);  break;
+      case '+':  t (fprintf(stdout, " ")                < 0);  break;
+      case '-':  t (fprintf(stdout, "\033[31m%c", *p++) < 0);  break;
+      }
+  t (fprintf(stdout, "\033[m\n") < 0);
+  
+  path_ = strchr(path + 1, '\0');
+  t (fprintf(stdout, "Correct: ") < 0);
+  for (p = correct; *--path_;)
+    switch (*path_)
+      {
+      case '=':  t (fprintf(stdout, "\033[39m%c", *p++) < 0);  break;
+      case '!':  t (fprintf(stdout, "\033[32m%c", *p++) < 0);  break;
+      case '+':  t (fprintf(stdout, "\033[32m%c", *p++) < 0);  break;
+      case '-':  t (fprintf(stdout, " ")                < 0);  break;
+      }
+  t (fprintf(stdout, "\033[m\n") < 0);
+  
+  rc = 1;
+ done:
+  free(entered);
+  free(path);
+  return rc;
+ fail:
+  rc = 1;
+  if (errno == 0)
+    goto done;
+  perror(argv0);
+  rc = 2;
+  goto done;
+ usage:
+  fprintf(stderr, "usage: %s YOUR-TELEPHONE-NUMBER\n", argv0);
+  return 2;
+}
+