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-rw-r--r--src/learn-your-telephone-number.c171
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;
+}
+