牛客堂常见面试题精讲（一）4

package com.zhao.niuke;

public class Problem_04 {
	public static String getPalindrome(String str, String strlps) {
		//str是给定一个字符串
		//strlps是最长回文子序列在任意位置添加字符后整体都是回文串的其中的一种结果
		if (str == null || str.equals("")) {
			return "";
		}//判空
		char[] chas = str.toCharArray();//将字符串先转换成字符数组
		char[] lps = strlps.toCharArray();//同理最小的这个串也转化成字符数组
		char[] res = new char[2 * chas.length - lps.length];//开辟存储空间用于存储返回的字符串
		int chasl = 0;//左边
		int chasr = chas.length - 1;//右边
		int lpsl = 0;//左边
		int lpsr = lps.length - 1;//右边
		int resl = 0;//左边
		int resr = res.length - 1;//右边
		int tmpl = 0;//左边
		int tmpr = 0;//右边
		while (lpsl <= lpsr) {
			tmpl = chasl;
			tmpr = chasr;
			//先从lps中第一个串的第一个字符和chas中的字符开始比较起，一个个比较找出相等的，也就是先找最左边的1
			while (chas[chasl] != lps[lpsl]) {
				chasl++;
			}
			//再从chas中找lps里面的最后一个元素在chas相等的，也就是找最右边的1
			while (chas[chasr] != lps[lpsr]) {
				chasr--;
			}
			//开始设置字符串的值
			set(res, resl, resr, chas, tmpl, chasl, chasr, tmpr);
			
			resl += chasl - tmpl + tmpr - chasr;
			resr -= chasl - tmpl + tmpr - chasr;
			res[resl++] = chas[chasl++];
			res[resr--] = chas[chasr--];
			lpsl++;
			lpsr--;
		}
		return String.valueOf(res);
	}
 public static void set(char[] res, int resl, int resr, char[] chas, int ls,
			int le, int rs, int re) {
		for (int i = ls; i < le; i++) {
			res[resl++] = chas[i];
			res[resr--] = chas[i];
		}
		for (int i = re; i > rs; i--) {
			res[resl++] = chas[i];
			res[resr--] = chas[i];
		}
	}
  public static void main(String[] args) {
	System.out.println("返回："+getPalindrome("AB1C2DE34F3GHJ21KL","1234321")); 
  }
}