Scramble string of leetcode

Scramble string

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"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 strings S1 and S2 of the same length, determine if S2 is a scrambled string of S1.

Analysis: Dynamic Planning. DP [I] [J] [k] indicates S1 [I ~ I + Len] and S2 [J ~ J + Len] whether it is scramble string, that is, whether S1 starts from I and S2 starts from J to scramble string. For each split point, determine whether the left and right sides are scramble strings. If one of them is satisfied, the substring will satisfy scramble string, that is

DP [I] [J] [Len] = (DP [I] [J] [k] & DP [I + k] [J + k] [Len-K]) | (DP [I] [J + len-K] [k] & DP [I + k] [J] [Len-K]), when Len = 1, DP [I] [J] [1] = S1 [I] = S2 [J].

Class solution {public: bool isscramble (string S1, string S2) {int length = s1.size (), I, J, K, Len; If (length! = S2.size () return false; vector <bool> dp (length); for (I = 0; I <length; ++ I) {vector <bool> tmp1 (length); For (j = 0; j <length; j ++) {vector <bool> tmp2 (Length + 1, false); tmp1 [J] = tmp2;} DP [I] = tmp1;} For (LEN = 1; Len <= length; Len ++) {for (I = 0; I + Len <= length; ++ I) {for (j = 0; j + Len <= length; ++ J) {If (LEN = 1) DP [I] [J] [Len] = (S1 [I] = S2 [J]); else {for (K = 1; k <Len; k ++) {If (DP [I] [J] [k] & DP [I + k] [J + k] [Len-K]) | (DP [I] [J + len-K] [k] & DP [I + k] [J] [Len-K]) {DP [I] [J] [Len] = true; // represents S1 [I ~ I + Len] and S2 [J ~ J + Len] whether it is scramble string break; }}}} return DP [0] [0] [length] ;}};

Scramble string of leetcode