update

written-exam/freewheel-onsite-2019/no2/Main.java

@@ -0,0 +1,49 @@
+import java.util.*;
+
+public class Main {
+    public static void main(String[] args) {
+        for (String str : split("")) {
+            System.out.printf("%s\t", str);
+        }
+        System.out.println();
+        for (String str : split(null)) {
+            System.out.printf("%s\t", str);
+        }
+        System.out.println();
+        for (String str : split("abc")) {
+            System.out.printf("%s\t", str);
+        }
+        System.out.println();
+        for (String str : split("abecadefgfg")) {
+            System.out.printf("%s\t", str);
+        }
+        System.out.println();
+    }
+
+    public static String[] split(String input) {
+        if (input == null) return new String[] {};
+        if (input.length() <= 1) return new String[] {input};
+        char[] chars = input.toCharArray();
+        int[] last = new int[256];
+        for (int i = 0; i < chars.length; i++) {
+            char ch = chars[i];
+            last[ch] = Math.max(last[ch], i);
+        }
+        int prev = 0;
+        int next = last[chars[0]];
+        List<String> list = new ArrayList<>();
+        for (int i = 0; i < chars.length; i++) {
+            char ch = chars[i];
+            if (i == next) {
+                list.add(input.substring(prev, i + 1));
+                prev = i + 1;
+                next = i == chars.length - 1 ? chars.length : last[chars[i + 1]];
+            } else {
+                next = Math.max(next, last[ch]);
+            }
+        }
+        String[] strs = new String[list.size()];
+        list.toArray(strs);
+        return strs;
+    }
+}