最长回文，没有效率的

package com.comp.string;

import java.util.*;

/*
 * w aa bwsw f d 
 */
public class LHWSTR {

	/*
	 * 采用递归实现
	 */
	public static String getLC(char[] test) {
		int length = test.length;

		return getLCC(test, 0, length - 1);
	}

	public static String getLCC(char[] test, int start, int end) {
		if (start < end) {
			if (check(test, start, end))
				return new String(test, start, end - start + 1);
			String str1 = getLCC(test, start + 1, end);
			String str2 = getLCC(test, start, end - 1);
			if (str1.length() > str2.length())
				return str1;
			else
				return str2;
		} else {
			return new String();
		}

	}

	public static boolean check(char[] test, int start, int end)

	{

		while (start < end) {

			if (test[start] == test[end]) {

				start++;
				end--;
				continue;
			}
			return false;
		}
		return true;
	}

	/*
	 * 采用回文中间点进行考察
	 */
	public static String getLCS(char[] test) {
		int length = test.length;
		int start = 0;
		int end = length - 1;
		List<String> lstr = new ArrayList<String>();
		List<String> rstr = new ArrayList<String>();

		/*
		 * 首先考虑最后的最大结果是奇数个回文,i不用考虑匹配
		 */
		for (int i = 0; i < length; i++) {
			int j = i - 1;
			int k = i + 1;

			while (start <= j && end >= k) {

				if (test[j] != test[k])
					break;
				j--;
				k++;

			}
			if ((j + 1) >= start && (k - 1) <= end)

				lstr.add(new String(test, j + 1, k - j - 1));

		}
		Iterator iter = lstr.iterator();
		int max = 0;
		String maxString = new String();
		while (iter.hasNext()) {
			String str = (String) iter.next();
			if (str.length() > max) {
				max = str.length();
				maxString = str;
			}
			

		}
		/*
		 * 考虑最后的结果是是偶数个回文
		 */
		for (int i = 0; i < length; i++) {
			int j = i;
			int k = i + 1;
			while (start <= j && end >= k) {
				if (test[j] != test[k])
					break;
				j--;
				k++;
			}
			if ((j + 1) >= start && (k - 1) <= end)

				lstr.add(new String(test, j + 1, k - j - 1));

		}
		Iterator iter2 = rstr.iterator();
		while (iter2.hasNext()) {
			String str = (String) iter2.next();
			if (str.length() > max) {
				max = str.length();
				maxString = str;
			}
			
		}
		return maxString;
	}

	public static void main(String args[]) {
		char[] test = { 'w', 'a', 'a', 'b', 'w', 's', 'w', 'f', 'd' };

		System.out.println(LHWSTR.getLCS(test));
	}

}