leetcode 87. Scramble String 二分法

leetcode 87. Scramble String

public class Solution {public static void main(String[] args){String s1 = "ab";String s2 = "ba";Solution s = new Solution();System.out.println(s.isScramble(s1, s2));}    public boolean isScramble(String s1, String s2) {        if(s1.equals(s2))  return true;        int[] letter = new int[26];        if(s1.length()!=s2.length())  return false;        for(int i=0;i<s1.length();i++){        letter[s1.charAt(i)-'a']++;        letter[s2.charAt(i)-'a']--;        }        for(int i=0;i<26;i++){        if(letter[i]!=0) return false;        }        for(int i=1;i<s1.length();i++){        if(isScramble(s1.substring(0,i),s2.substring(0,i))&&        isScramble(s1.substring(i),s2.substring(i)))  return true;        if(isScramble(s1.substring(0,i),s2.substring(s2.length()-i))        &&isScramble(s1.substring(i),s2.substring(0,s2.length()-i)))  return true;        }    return false;    }}