From 975c201dbd7bd60f3333d9cc82993146be062026 Mon Sep 17 00:00:00 2001
From: Nigesh Shakya <nigesh.shakya@cerner.com>
Date: Fri, 9 Oct 2020 19:05:18 -0500
Subject: [PATCH] Added a leetcode solution for problem 0091 Decode Ways for
 hacktoberfest

---
 LeetCode/0091_Decode_Ways.py | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 LeetCode/0091_Decode_Ways.py

diff --git a/LeetCode/0091_Decode_Ways.py b/LeetCode/0091_Decode_Ways.py
new file mode 100644
index 0000000..e5d83ff
--- /dev/null
+++ b/LeetCode/0091_Decode_Ways.py
@@ -0,0 +1,20 @@
+class Solution:
+    def numDecodings(self, s: str) -> int:
+        def in_range(n):
+            if n[0] == '0':
+                return False
+            to_int = int(n)
+            if to_int <= 26 and to_int > 0:
+                return True
+            return False
+        
+        N = len(s)
+        a, b = 1, 1
+        if N == 0 or s[0] == '0':
+            return 0
+        
+        for i in range(1, N):
+            extra = a if in_range(s[i-1:i+1]) else 0
+            c = extra + (b if in_range(s[i]) else 0)
+            a, b = b, c
+        return b