fix: fixed validator and added input file and checker.

ra-preguicosa/src/checker.cpp

@@ -1,12 +1,33 @@
 #include "testlib.h"
-#include <bits/stdc++.h>
-
+#include <string>
 
 using namespace std;
 
-
-int main(int argc, char* argv[]) {
-    setName("Set the name of your checker here");
+int main(int argc, char *argv[]) {
+    setName("compare files as sequence of lines");
     registerTestlibCmd(argc, argv);
-    return 0;
+
+    std::string strAnswer;
+
+    int n = 0;
+    while (!ans.eof()) {
+        std::string j = ans.readString();
+
+        if (j.empty() && ans.eof())
+            break;
+
+        strAnswer = j;
+        std::string p = ouf.readString();
+
+        n++;
+
+        if (j != p)
+            quitf(_wa, "%d%s lines differ - expected: '%s', found: '%s'", n, englishEnding(n).c_str(),
+                  compress(j).c_str(), compress(p).c_str());
+    }
+
+    if (n == 1)
+        quitf(_ok, "single line: '%s'", compress(strAnswer).c_str());
+
+    quitf(_ok, "%d lines", n);
 }