refactor

Bench4Q-Agent/src/test/java/org/bench4q/agent/test/Solution.java

@@ -0,0 +1,81 @@
+package org.bench4q.agent.test;
+
+import static org.junit.Assert.*;
+
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.Queue;
+import java.util.Set;
+
+import org.junit.Test;
+
+public class Solution {
+	private static String LEVEL_END = "LEVEL_END";
+
+	public int ladderLength(String start, String end, Set<String> dict) {
+		int result = 1;
+		Set<String> footPrints = new HashSet<String>();
+		Queue<String> level = new LinkedList<String>();
+
+		level.offer(start);
+		level.offer(LEVEL_END);
+		while (!level.isEmpty()) {
+			result++;
+			String temp = level.poll();
+			if (temp.equals(LEVEL_END)) {
+				result++;
+				if (level.isEmpty()) {
+					continue;
+				}
+				level.offer(LEVEL_END);
+				continue;
+			}
+			for (String neighbor : getNeighbors(temp, dict)) {
+				if (!hasVisited(footPrints, neighbor)) {
+					footPrints.add(neighbor);
+					level.offer(neighbor);
+					if (neighbor.equals(end)) {
+						return result;
+					}
+				}
+			}
+		}
+		return 0;
+	}
+
+	private boolean hasVisited(Set<String> footPrints, String neighbor) {
+		return footPrints.contains(neighbor);
+	}
+
+	private Set<String> getNeighbors(String target, Set<String> dict) {
+		String temp = "";
+		Set<String> result = new HashSet<String>();
+		for (int i = 0; i < target.length(); i++) {
+			for (char c = 'a'; c < 'z'; c++) {
+				temp = buildNewStart(target, i, c);
+				if (temp.equals(target)) {
+					continue;
+				}
+				if (dict.contains(temp)) {
+					result.add(temp);
+				}
+			}
+		}
+		return result;
+	}
+
+	private String buildNewStart(String toBeChanged, int index, char replace) {
+		return toBeChanged.substring(0, index) + replace
+				+ toBeChanged.substring(index + 1);
+	}
+
+	@Test
+	public void test() {
+		Solution solution = new Solution();
+		assertEquals(
+				2,
+				solution.ladderLength("a", "c",
+						new HashSet<String>(Arrays.asList("a", "b", "c"))));
+	}
+}