September 2017 Update

Task/Increment-a-numerical-string/C/increment-a-numerical-string-1.c

@@ -1,70 +0,0 @@
-#include <stdio.h>
-#include <string.h>
-#include <stdlib.h>
-
-/*  Constraints: input is in the form of (\+|-)?[0-9]+
- *  and without leading zero (0 itself can be as "0" or "+0", but not "-0");
- *  input pointer is realloc'able and may change;
- *  if input has leading + sign, return may or may not keep it.
- *  The constranits conform to sprintf("%+d") and this function's own output.
- */
-char * incr(char *s)
-{
-	int i, begin, tail, len;
-	int neg = (*s == '-');
-	char tgt = neg ? '0' : '9';
-
-	/* special case: "-1" */
-	if (!strcmp(s, "-1")) {
-		s[0] = '0', s[1] = '\0';
-		return s;
-	}
-
-	len = strlen(s);
-	begin = (*s == '-' || *s == '+') ? 1 : 0;
-
-	/* find out how many digits need to be changed */
-	for (tail = len - 1; tail >= begin && s[tail] == tgt; tail--);
-
-	if (tail < begin && !neg) {
-		/* special case: all 9s, string will grow */
-		if (!begin) s = realloc(s, len + 2);
-		s[0] = '1';
-		for (i = 1; i <= len - begin; i++) s[i] = '0';
-		s[len + 1] = '\0';
-	} else if (tail == begin && neg && s[1] == '1') {
-		/* special case: -1000..., so string will shrink */
-		for (i = 1; i < len - begin; i++) s[i] = '9';
-		s[len - 1] = '\0';
-	} else { /* normal case; change tail to all 0 or 9, change prev digit by 1*/
-		for (i = len - 1; i > tail; i--)
-			s[i] = neg ? '9' : '0';
-		s[tail] += neg ? -1 : 1;
-	}
-
-	return s;
-}
-
-void string_test(const char *s)
-{
-	char *ret = malloc(strlen(s));
-	strcpy(ret, s);
-
-	printf("text: %s\n", ret);
-	printf("  ->: %s\n", ret = incr(ret));
-	free(ret);
-}
-
-int main()
-{
-	string_test("+0");
-	string_test("-1");
-	string_test("-41");
-	string_test("+41");
-	string_test("999");
-	string_test("+999");
-	string_test("109999999999999999999999999999999999999999");
-	string_test("-100000000000000000000000000000000000000000000");
-
-	return 0;
-}

Task/Increment-a-numerical-string/C/increment-a-numerical-string-2.c

@@ -1,16 +0,0 @@
-text: +0
-  ->: +1
-text: -1
-  ->: 0
-text: -41
-  ->: -40
-text: +41
-  ->: +42
-text: 999
-  ->: 1000
-text: +999
-  ->: 1000
-text: 109999999999999999999999999999999999999999
-  ->: 110000000000000000000000000000000000000000
-text: -100000000000000000000000000000000000000000000
-  ->: -99999999999999999999999999999999999999999999