Leetcode: Scramble string

Leetcode: Scramble string

Given a stringS1, We may represent it as a binary tree by partitioning it to two non-empty substrings recursively.

Below is one possible representationS1="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"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"great".

Given two stringsS1AndS2Of the same length, determine ifS2Is a scrambled stringS1.

Address: https://oj.leetcode.com/problems/scramble-string/

Algorithm: If the string S1 [0 ~ I] and S2 [0 ~ I] and S1 [I + 1 ~ N] and S2 [I + 1 ~ N] all meet the scrambled condition, so S1 and S2 are also met; if the string S1 [0 ~ I] and S2 [n-I ~ N] and S1 [I + 1 ~ N] and S2 [0 ~ N-i-1] Meet scrambled conditions, then S1 and S2 also meet, where I = 1... n. Note: Before recursive calling, use the isreasonstring function to determine whether the scrambled condition may be satisfied, which can reduce the number of recursion times. Code:

 1 class Solution { 2 public: 3     bool isScramble(string s1, string s2) { 4         if(s1 == s2){ 5             return true; 6         }     7         if(s1.size() == 1){ 8             return false; 9         }10         int len = s1.size();11         for(int i = 1; i < len; ++i){12             string s11 = s1.substr(0,i);13             string s21 = s2.substr(0,i);14             string s12 = s1.substr(i,len-i);15             string s22 = s2.substr(i,len-i);16             if(isReasonString(s11,s21) && isReasonString(s12,s22) && isScramble(s11,s21) && isScramble(s12,s22)){17                 return true;18             }19             s21 = s2.substr(len-i,i);20             s22 = s2.substr(0,len-i);21             if(isReasonString(s11,s21)  && isReasonString(s12,s22) && isScramble(s11,s21) && isScramble(s12,s22)){22                 return true;23             }24         }25         return false;26     }27     bool isReasonString(string s1, string s2){28         sort(s1.begin(),s1.end());29         sort(s2.begin(),s2.end());30         return s1 == s2;31     }32 };

 

Leetcode: Scramble string