added Divisibility of Strings

Author: minhyeong-joe

README.md

@@ -128,6 +128,7 @@ Languages used: Java and Python
 
 ### [String](./String)
 
+- [Divisibility of Strings](String/DivisibilityOfStrings)
 - [Isomorphic Strings](String/IsomorphicStrings)
 - [Longest Common Prefix](String/LongestCommonPrefix)
 - [Minimum Steps to Make Two Strings Anagram](String/MinStepsToMakeTwoStringsAnagram)

String/DivisibilityOfStrings/README.md

@@ -0,0 +1,5 @@
+# Divisibility of Strings
+
+[Leetcode Link](https://leetcode.com/discuss/general-discussion/680341/Divisibility-of-Strings)
+
+![prompt](./prompt.png)

String/DivisibilityOfStrings/prompt.png

@@ -0,0 +1,24 @@
+def divisible(s: str, t: str) -> int:
+    # this edge case catch is optional because of problem constraints
+    if len(s) < len(t) or len(s) == 0 or len(t) == 0:
+        return -1
+    # if length is not divisible
+    if len(s) % len(t) != 0:
+        return -1
+    # find smallest common string of two
+    # bcdbcdbcdbcd[1:-1] -> cdbcdbcdbc.find(bcdbcd) -> 2
+    i = (t+t)[1:-1].find(t)
+    smallestString = t[i+1:]    # bcdbcd[3:] -> bcd
+    # print(smallestString)
+    # check if s is also repeating smallest string
+    while len(t) < len(s):
+        t += t
+        if s == t:
+            return len(smallestString)
+        else:
+            return -1
+
+
+s = "bcdbcdbcdbcd"
+t = "bcdbcd"
+print(divisible(s, t))