add fastscanner

java/reverse/Reverse.java

@@ -1,49 +1,81 @@
 package reverse;
 
-import java.util.ArrayList;
-import java.util.Scanner;
+import java.io.*;
+import java.util.Arrays;
 
 public class Reverse {
-    public static void main(String[] args) {
-        Scanner sc = new Scanner(System.in);
-        ArrayList<ArrayList<String>> lines = new ArrayList<>();
+    public static void main(String[] args) throws IOException {
+        FastScanner sc = new FastScanner();
+        int[][] lines = new int[8][];
+        int linesCount = 0;
 
         while (sc.hasNextLine()) {
-            ArrayList<String> line = new ArrayList<>();
-            StringBuilder builder = new StringBuilder();
-            String lineString = sc.nextLine();
+            int[] line = new int[8];
+            int count = 0;
 
-            for (char c : lineString.toCharArray()) {
-                if (!Character.isWhitespace(c)) {
-                    builder.append(c);
-                } else {
-                    if (!builder.toString().isEmpty()) {
-                        line.add(builder.toString());
-                    }
-                    builder = new StringBuilder();
+            while (sc.hasNextInt()) {
+                if (count >= line.length) {
+                    line = Arrays.copyOf(line, line.length * 2);
                 }
+                line[count++] = sc.nextInt();
             }
-            if (!builder.toString().isEmpty()) {
-                line.add(builder.toString());
+            sc.nextLine();
+
+            line = Arrays.copyOf(line, count);
+
+            if (linesCount >= lines.length) {
+                lines = Arrays.copyOf(lines, lines.length * 2);
             }
-            lines.add(line);
+            lines[linesCount++] = line;
         }
 
-        sc.close();
-
-
-
-        for (int i = lines.size() - 1; i >= 0; i--) {
-            if (lines.get(i).isEmpty()) {
-                System.out.println();
+        PrintWriter out = new PrintWriter(System.out);
+        for (int i = linesCount - 1; i >= 0; i--) {
+            int[] line = lines[i];
+            for (int j = line.length - 1; j >= 0; j--) {
+                if (j < line.length - 1) out.print(" ");
+                out.print(line[j]);
             }
-            for (int j = lines.get(i).size() - 1; j >= 0; j--) {
-                if (j > 0) {
-                    System.out.print(lines.get(i).get(j) + " ");
-                } else {
-                    System.out.println(lines.get(i).get(j));
-                }
+            out.println();
+        }
+        out.flush();
+    }
+
+    static class FastScanner {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        String line = null;
+        int pos = 0;
+
+        boolean hasNextLine() throws IOException {
+            if (line != null && pos < line.length()) return true;
+            line = br.readLine();
+            pos = 0;
+            return line != null;
+        }
+
+        boolean hasNextInt() {
+            if (line == null) return false;
+            while (pos < line.length() && Character.isWhitespace(line.charAt(pos))) pos++;
+            return pos < line.length();
+        }
+
+        int nextInt() {
+            while (pos < line.length() && Character.isWhitespace(line.charAt(pos))) pos++;
+            int start = pos;
+            boolean negative = line.charAt(pos) == '-';
+            if (negative) pos++;
+
+            while (pos < line.length() && Character.isDigit(line.charAt(pos))) pos++;
+
+            int result = 0;
+            for (int i = negative ? start + 1 : start; i < pos; i++) {
+                result = result * 10 + (line.charAt(i) - '0');
             }
+            return negative ? -result : result;
+        }
+
+        void nextLine() {
+            pos = line.length();
         }
     }
 }

java/reverse/test.dat

@@ -0,0 +1,2 @@
+1 2
+3