Scramble String (Java)

Scramble String

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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.

	/*
	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.
	*/
	public class ScrambleString {
	public boolean isScramble(String s1, String s2) {
	if( s1==null||s2==null){
	return false;
	}
	if (s1.length()==0){
	return s2.length()==0;
	}
	if (s1.length()!=s2.length()){
	return false;
	}
	if (s1.equals(s2)){
	return true;
	}
	int value1=0;
	int value2=0;
	// check is s1 and s2 has same chars
	for (int i=0; i<s1.length(); i++){
	value1+=s1.charAt(i)-'0';
	value2+=s2.charAt(i)-'0';
	}
	if (value1!=value2){
	return false;
	}
	for (int i =1; i<s1.length(); i++){
	String s1Left=s1.substring(0, i);
	String s1Right=s1.substring(i);
	String s2Left=s2.substring(0,i);
	String s2Right=s2.substring(i);
	if (isScramble(s1Left, s2Left)&&isScramble(s1Right,s2Right)){
	return true;
	}
	s2Left=s2.substring(s2.length()-i);
	s2Right=s2.substring(0, s2.length()-i);
	if (isScramble(s1Left, s2Left)&&isScramble(s1Right,s2Right)){
	return true;
	}
	}
	return false;
	}
	}

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