标签:dp
A message containing letters from A-Z
is
being encoded to numbers using the following mapping:
‘A‘ -> 1 ‘B‘ -> 2 ... ‘Z‘ -> 26
Given an encoded message containing digits, determine the total number of ways to decode it.
For example,
Given encoded message "12"
,
it could be decoded as "AB"
(1
2) or "L"
(12).
The number of ways decoding "12"
is
2.
#include<iostream> #include<vector> #include<string> using namespace std; int numDecodings(string s) { if (s.empty()) return 0; vector<int>Decway(s.size()+1,0); Decway[0]= s[0]!='0'?1:0; Decway[1] =s[0]!='0'?1:0; for (int i = 2;i<Decway.size();++i) { int tmp = 10*(s[i-2]-'0')+s[i-1]-'0'; if (s[i-1]=='0') { if (tmp<=26&&tmp>=10&&tmp!=0) Decway[i] =Decway[i-2]; else Decway[i] =0; } else { if (tmp<10||tmp>26||tmp==0) Decway[i] =Decway[i-1]; else Decway[i] =Decway[i-1]+Decway[i-2]; } } return Decway[s.size()]; }
标签:dp
原文地址:http://blog.csdn.net/li_chihang/article/details/44828259