fix: corrected checker to validate both participant and judge answer.

longest-increasing-subsequence/problem.json

@@ -11,7 +11,7 @@
         "grader": false,
         "subject": {
             "en_us": [
-                "dynamic-programming", "longest-increasing-subsequence"
+                "dynamic-programming", "longest-increasing-subsequence", "LIS"
             ],
             "pt_br": [
                 "programação-dinâmica", "maior-subsequência-crescente"

longest-increasing-subsequence/src/checker.cpp

@@ -3,19 +3,35 @@
 
 using namespace std;
 
-bool isPaAnswerOk(vector<int> &nums, vector<int> &ans) {
+int readAns(InStream& stream, vector<int>& nums) {
+    
+    int size = stream.readInt(1, 1e3);
+    vector<int> ans;
+    while (!stream.seekEof())
+        ans.push_back(stream.readInt());
+
+    if (size != ans.size())
+        quitf(_wa, "Subsequence does not match size provided");
+
     for (int i = 1; i < ans.size(); i++) {
-        if (ans[i - 1] >= ans[i]) return false;
+        if (ans[i - 1] >= ans[i]) {
+            quitf(_wa, "Subsequence is not strictly increasing");
+        }
     }
 
+    // checking if numbers provided are indeed a subsequence of the original array
     int j = 0;
-    for (int i = 0, j = 0; i < nums.size() && j < ans.size(); i++) {
+    for (int i = 0; i < nums.size() && j < ans.size(); i++) {
         if (nums[i] == ans[j]) {
             j++;
         }
     }
 
-    return j == (int)ans.size();
+    if (j != size) {
+        quitf(_wa, "The provided subsequence is not present in the original array");
+    }
+
+    return size;
 }
 
 
@@ -27,18 +43,8 @@ int main(int argc, char* argv[]) {
     vector<int> nums(n);
     for (int i = 0; i < n; i++) nums[i] = inf.readInt();
 
-    int ja = ans.readInt();
-    int pa = ouf.readInt(1, 1e3);
-
-    vector<int> paAns;
-    while (!ouf.seekEof())
-        paAns.push_back(ouf.readInt());
-
-    if (pa != paAns.size())
-        quitf(_wa, "Subsequence does not match size provided");
-    
-    if (!isPaAnswerOk(nums, paAns))
-        quitf(_wa, "Subsequence does not match the constraints");
+    int ja = readAns(ans, nums);
+    int pa = readAns(ouf, nums);
 
     if (ja > pa)
         quitf(_wa, "Expected (%i) found (%i)", ja, pa);