Merge pull request #536 from neaGaze/feature/0091_decode_ways

Added a leetcode solution for problem 0091 Decode Ways for hacktoberfest

Author: vJechsmayr

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