add all variants for 'Sum' task (hw2)

java/sum/SumLongOctal.java

@@ -0,0 +1,41 @@
+package sum;
+
+import java.math.BigInteger;
+
+/**
+ * @author Nikita Doschennikov (me@fymio.us)
+ */
+public class SumLongOctal {
+    public static void main(String[] args) {
+        long res = 0;
+        for (String arg : args) {
+            StringBuilder builder = new StringBuilder();
+            for (char c : arg.toCharArray()) {
+                if (!Character.isWhitespace(c)) {
+                    builder.append(c);
+                } else {
+                    res += compute(builder.toString());
+                    builder = new StringBuilder();
+                }
+            }
+            res += compute(builder.toString());
+        }
+        System.out.println(res);
+    }
+
+    static long compute(String num) {
+        if (num.isEmpty()) {
+            return 0L;
+        }
+
+        if (num.endsWith("o") || num.endsWith("O")) {
+            String oct = num.substring(0, num.length() - 1);
+
+            BigInteger bi = new BigInteger(oct, 8);
+
+            return bi.longValue();
+        } else {
+            return Long.parseLong(num);
+        }
+    }
+}