lintcode 解码方法

简单的动态规划

 class Solution {
 public:

     /*
      * @param s: a string,  encoded message
      * @return: an integer, the number of ways decoding
      */
     int numDecodings(string s) {
         // write your code here
         if(s == "" || s[] == '') return ;
         int dp[];

         memset(dp, , sizeof(dp));
         dp[] = ;
         for(int i = ; i < s.length(); ++i){
                 if(s[i] == ''){
                     if(s[i - ] != '' && s[i -] != '') return ;
                     else {
                         dp[i] = dp[i] + (i -  >=  ? dp[i-] : );
                     }
                 } else {
                     if(s[i - ] == ''){
                         dp[i] = dp[i] + (i -  >=  ? dp[i-] : );
                         dp[i] = dp[i] + dp[i - ];
                     } else if(s[i - ] == ''){
                         if(s[i] <= '')
                             dp[i] = dp[i] + (i -  >=  ? dp[i-] : );
                         dp[i] = dp[i] + dp[i - ];
                     } else {
                         dp[i] = dp[i] + dp[i - ];
                     }
                 }
         }

         return dp[s.length() - ];
     }
 };