feat(392-is-subsequence): added py3 soln and readme

0392_is-subsequence/python3/main.py

@@ -0,0 +1,37 @@
+class Solution:
+    def isSubsequence(self, s: str, t: str) -> bool:
+        slen = len(s)
+        tlen = len(t)
+        si = 0
+        ti = 0
+        
+        # If s is longer than t, it's obviously not
+        # going to be a subsequence
+        if slen > tlen:
+            return False
+        
+        while ti < tlen and si < slen:
+            found = False
+            
+            while ti < tlen:
+                if s[si] == t[ti]:
+                    found = True
+                    ti += 1
+                    break
+
+                ti += 1
+            
+            if not found:
+                return False
+            
+            si += 1
+        
+        # We reached end of t but we still have
+        # characters remaining in s and hence
+        # it's not a subsequence
+        if si < slen:
+            return False
+            
+        return True
+        
+