fix round 1

tasks/easy/grader.py

@@ -1,9 +1,3 @@
 def grade(rewards):
     score = sum(rewards) / len(rewards)
-
-    if score >= 0.4:
-        return 1.0
-    elif score >= 0.2:
-        return 0.5
-    else:
-        return 0.0
+    return min(max(score, 0.0), 1.0)

tasks/hard/grader.py

@@ -1,9 +1,4 @@
 def grade(rewards):
     score = sum(rewards) / len(rewards)
-
-    if score >= 0.6:
-        return 1.0
-    elif score >= 0.4:
-        return 0.7
-    else:
-        return 0.3
+    score = score * 0.8
+    return min(max(score, 0.0), 1.0)

tasks/medium/grader.py

@@ -1,9 +1,4 @@
 def grade(rewards):
     score = sum(rewards) / len(rewards)
-
-    if score >= 0.5:
-        return 1.0
-    elif score >= 0.3:
-        return 0.6
-    else:
-        return 0.2
+    score = score * 0.9
+    return min(max(score, 0.0), 1.0)