Merge pull request #68 from abhishekyadav13/patch-1

recursive solution

ScrambleString.cpp

@@ -0,0 +1,42 @@
+/*
+We can scramble a string s to get a string t using the following algorithm:
+
+If the length of the string is 1, stop.
+If the length of the string is > 1, do the following:
+Split the string into two non-empty substrings at a random index, i.e., if the string is s, divide it to x and y where s = x + y.
+Randomly decide to swap the two substrings or to keep them in the same order. i.e., after this step, s may become s = x + y or s = y + x.
+Apply step 1 recursively on each of the two substrings x and y.
+Given two strings s1 and s2 of the same length, return true if s2 is a scrambled string of s1, otherwise, return false.
+
+*/
+
+class Solution {
+public:
+    bool isScramble(string s1, string s2) {
+        if(s1==s2)
+            return true;
+
+        int len = s1.length();
+        int count[26] = {0};
+        for(int i=0; i<len; i++)
+        {
+            count[s1[i]-'a']++;
+            count[s2[i]-'a']--;
+        }
+
+        for(int i=0; i<26; i++)
+        {
+            if(count[i]!=0)
+                return false;
+        }
+
+        for(int i=1; i<=len-1; i++)
+        {
+            if( isScramble(s1.substr(0,i), s2.substr(0,i)) && isScramble(s1.substr(i), s2.substr(i)))
+                return true;
+            if( isScramble(s1.substr(0,i), s2.substr(len-i)) && isScramble(s1.substr(i), s2.substr(0,len-i)))
+                return true;
+        }
+        return false;
+    }
+};