Add unique chars check

data_structures/strings/unique_chars.py

@@ -0,0 +1,26 @@
+"""
+Check if a string has unique chars
+
+    How it works:
+        - The total number of characters that a string can be built of is 128 chars,
+          so if a string is longer than 128 chars, then it must have repeated chars.
+        - if it's 128 or less, then check using two nested for loops.
+"""
+def unique_chars(s):
+    lenS = len(s)
+    if lenS > 128:
+        return False
+    for i in range(lenS-1):
+        for j in range(i+1,lenS):
+            if s[j]==s[i]:
+                return False
+    return True
+
+
+s1 = "goToSchool"
+s2 = "getAjob"
+s3 = "A"
+
+print("%s is: " %s1, unique_chars(s1), '\n')
+print("%s is: " %s2, unique_chars(s2), '\n')
+print("%s is: " %s3, unique_chars(s3), '\n')