WordReplacer.java

package org.psjava.judgesubmit;

import java.util.HashMap;
import java.util.Map;
import java.util.Set;

public class WordReplacer {

	public static String getReplaced(String original, Set<String> words) {
		Map<String, String> matchMap = constructMatchingMap(original, words);
		return getReplacedByMap(original, matchMap);
	}

	private static Map<String, String> constructMatchingMap(String original, Set<String> words) {
		Map<String, String> matchMap = new HashMap<String, String>();
		int index = 0;
		for (String word : words) {
			String candidate;
			while(true) {
				candidate = Integer.toString(index++, 10 + 26);
				if(Character.isLetter(candidate.charAt(0)) && !original.contains(candidate))
					break;
			}
			matchMap.put(word, candidate);
		}
		return matchMap;
	}

	private static String getReplacedByMap(String original, Map<String, String> matchMap) {
		StringBuilder out = new StringBuilder();
		String word = "";
		for (int i = 0; i < original.length(); i++) {
			char c = original.charAt(i);
			if (Character.isLetter(c) || Character.isDigit(c)) {
				word += c;
			} else {
				outputReplacedWordIfPossible(word, out, matchMap);
				word = "";
				out.append(c);
			}
		}
		outputReplacedWordIfPossible(word, out, matchMap);
		return out.toString();
	}

	private static void outputReplacedWordIfPossible(String w, StringBuilder out, Map<String, String> matchMap) {
		if (w.length() > 0) {
			String v = matchMap.get(w);
			if (v == null)
				out.append(w);
			else
				out.append(v);
		}
	}
}