[Leetcode]91 Decode Ways

https://oj.leetcode.com/problems/decode-ways/

http://blog.csdn.net/linhuanmars/article/details/24570759

Public class solution {    public int numdecodings (String s)     {        if  (s == null | |  s.length ()  == 0)             return  0;   // invalid input                     char[] chars = s.tochararray ( );                if  ( chars[0] ==  ' 0 ')             return  0;                int[]  ways = new int[chars.length];        ways[0] =  1;                for  (int i =  1 ; i < chars.length ; i ++)          {            char c =  chars[i];            char lastc =  chars[i - 1];                         if  (c ==  ' 0 ')              {                 if  (lastc ==  ' 1 '  | |  lastc ==  ' 2 ')                  {                    if  (i == 1)                          ways[i] = 1;                     else                          ways[i] = ways[i - 2];                 }                 else                     return 0;             }            else // not 0             {                 if  (lastc ==  ' 0 '  | |  lastc >  ' 2 ')     // Cannot 2 char                     ways[i] =  ways[i - 1];                 else if  (lastc ==  ' 2 '  && c >  ' 6 '   && c <= ' 9 ')                      ways[i] = ways[i - 1];                 else if  (i == 1)                      ways[i] = 2;                 else                     ways[i] =  ways[i - 1] + ways[i - 2];             }        }                 return ways[chars.length - 1];     }}

[Leetcode]91 Decode Ways