refactor: simplify Main structure and add assertion in p2190B1

Author: lzwjava

src/main/java/com/lzw/solutions/codeforces/p2190B1/Main.java

@@ -31,6 +31,7 @@ private void solve() throws IOException {
         while (t-- > 0) {
             int n = Integer.parseInt(in.readLine());
             String s = in.readLine();
+            assert (s.length() == n);
             out.println(s);
         }
     }

src/main/java/com/lzw/solutions/sample/pjava_sample_buf/Main.java

@@ -1,40 +1,17 @@
 package com.lzw.solutions.sample.pjava_sample_buf;
 
-import java.io.BufferedReader;
-import java.io.IOException;
-import java.io.InputStreamReader;
-import java.io.PrintWriter;
+import java.io.*;
 
 public class Main {
+    private static final BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
+    private static final PrintWriter out = new PrintWriter(System.out, true);
 
-    BufferedReader in;
-    PrintWriter out;
-
-    Main() {
-        in = new BufferedReader(new InputStreamReader(System.in));
-        out = new PrintWriter(System.out);
-    }
-
-    int readInt() throws IOException {
-        return Integer.parseInt(in.readLine());
+    private static void solve() throws IOException {
+        // your code here
     }
 
-    void solve() throws IOException {}
-
-    void close() throws IOException {
-        if (in != null) {
-            in.close();
-        }
-        if (out != null) {
-            out.flush();
-            out.close();
-        }
-    }
-
-    public static void main(String[] args) throws Exception {
-
-        Main main = new Main();
-        main.solve();
-        main.close();
+    public static void main(String[] args) throws IOException {
+        solve();
+        out.close();
     }
-}
+}