problem_settings: fix float regex

A missing `*` was unfortunately not caught during review. Added a
regression test.

Author: Riolku

sample_files/problem_setting/identical_checker_interactor.cpp

@@ -106,7 +106,7 @@ long long readInt(long long lo, long long hi) {
 
 long double readFloat(long double min, long double max,
                       long double eps = 1e-9) {
-  static regex_t re = regex_helpers::compile("^-?(0|[1-9][0-9])(\\.[0-9]+)?$");
+  static regex_t re = regex_helpers::compile("^-?(0|[1-9][0-9]*)(\\.[0-9]+)?$");
   std::string token = readToken();
   assertWA(regex_helpers::match(re, token));
   long double parsedDouble;

sample_files/problem_setting/standard_checker_interactor.cpp

@@ -149,7 +149,7 @@ long long readInt(long long lo, long long hi) {
 
 long double readFloat(long double min, long double max,
                       long double eps = 1e-9) {
-  static regex_t re = regex_helpers::compile("^-?(0|[1-9][0-9])(\\.[0-9]+)?$");
+  static regex_t re = regex_helpers::compile("^-?(0|[1-9][0-9]*)(\\.[0-9]+)?$");
   std::string token = readToken();
   assertWA(regex_helpers::match(re, token));
   long double parsedDouble;

sample_files/problem_setting/test/testsuite/identical_checker_interactor/cases/basic2/code

@@ -0,0 +1 @@
+0

sample_files/problem_setting/test/testsuite/identical_checker_interactor/cases/basic2/input

@@ -0,0 +1,2 @@
+1
+1.76

sample_files/problem_setting/test/testsuite/identical_checker_interactor/cases/basic2/output

@@ -0,0 +1 @@
+1.76

sample_files/problem_setting/validator.cpp

@@ -64,7 +64,7 @@ long long readInt(long long lo, long long hi) {
 
 long double readFloat(long double min, long double max,
                       long double eps = 1e-9) {
-  static regex_t re = regex_helpers::compile("^-?(0|[1-9][0-9])(\\.[0-9]+)?$");
+  static regex_t re = regex_helpers::compile("^-?(0|[1-9][0-9]*)(\\.[0-9]+)?$");
   std::string token = readToken();
   assert(regex_helpers::match(re, token));
   long double parsedDouble = stold(token); // May throw.