Given a string s1, we may represent it as a binary tree by partitioning it to two non-empty substrings recursively.
Below is one possible representation of s1 =
"great"
:great / \ gr eat / \ / \ g r e at / \ a t
To scramble the string, we may choose any non-leaf node and swap its two children.
For example, if we choose the node
"gr"
and swap its two children, it produces a scrambled string "rgeat"
.rgeat / \ rg eat / \ / \ r g e at / \ a t
We say that
"rgeat"
is a scrambled string of "great"
.
Similarly, if we continue to swap the children of nodes
"eat"
and "at"
, it produces a scrambled string "rgtae"
.rgtae / \ rg tae / \ / \ r g ta e / \ t a
We say that
"rgtae"
is a scrambled string of "great"
.
Given two strings s1 and s2 of the same length, determine if s2 is a scrambled string of s1.
Understand the problem:public class Solution { public boolean isScramble(String s1, String s2) { if (s1.length() != s2.length()) { return false; } if (s1.length() == 1 && s2.length() == 1) { if (s1.charAt(0) == s2.charAt(0)) { return true; } else { return false; } } char[] array1 = s1.toCharArray(); char[] array2 = s2.toCharArray(); Arrays.sort(array1); Arrays.sort(array2); if (!Arrays.toString(array1).equals(Arrays.toString(array2))) { return false; } for (int i = 1; i < s1.length(); i++) { String s11 = s1.substring(0, i); String s12 = s1.substring(i); String s21 = s2.substring(0, i); String s22 = s2.substring(i); if (isScramble(s11, s21) && isScramble(s12, s22)) { return true; } s21 = s2.substring(0, s2.length() - i); s22 = s2.substring(s2.length() - i); if (isScramble(s11, s22) && isScramble(s12, s21)) { return true; } } return false; } }
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