package com.klvchen.exer;

import org.junit.Test;

import java.util.Arrays;

public class StringDemo2 {
    /*
    获取两个字符串中最大相同子串,比如:
    str1 = "abcwerthelloyuiodef" ; str2 = "cvhellobnm"
    提示:将短的那个串进行长度依次递减的子串与较长的串比较。
     */

    public String getMaxSameString(String str1, String str2){
        String maxStr = (str1.length() >= str2.length())? str1 : str2;
        String minStr = (str1.length() <  str2.length())? str1 : str2;
        int length = minStr.length();

        for (int i = 0; i < length; i++){
            for (int x = 0, y = length - i; y <= length; x++, y++){
                String subStr = minStr.substring(x, y);
                if (maxStr.contains(subStr)){
                    return subStr;
                }
            }
        }

        return null;
    }

    // 如果存在多个长度相同的最大相同子串
    // 此时先返回 String[], 后面可以用集合中的 ArrayList 替换，较方便
    public String[] getMaxSameString1(String str1, String str2){
        if (str1 != null && str2 != null){
            StringBuffer sBuffer = new StringBuffer();
            String maxString = (str1.length() > str2.length()) ? str1 : str2;
            String minString = (str1.length() > str2.length()) ? str2 : str1;

            int len = minString.length();
            for (int i = 0; i < len; i++){
                for (int x = 0, y = len - i; y <= len; x++, y++){
                    String subString = minString.substring(x, y);
                    if (maxString.contains(subString)){
                        sBuffer.append(subString + ",");
                    }
                }
//                System.out.println(sBuffer);
                if (sBuffer.length() != 0){
                    break;
                }
            }
            String[] split = sBuffer.toString().replaceAll(",$", "").split("\\,");
            return split;
        }

        return null;
    }

    @Test
    public void testGetMaxSameString(){
        String str1 = "abcwerthelloyuiodef";
        String str2 = "cvhellobnm";
        String[] maxSameStrings = getMaxSameString1(str1, str2);
        System.out.println(Arrays.toString(maxSameStrings));
    }
}

Java 练习(获取两个字符串中最大相同子串)