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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.
Dynamic Programming String
class Solution { int m_cnt; public: void numDecode(int dep, string s) { if(dep == s.size()) { m_cnt ++; return; } numDecode(dep+1, s); if((dep+1) < s.size()) { if( (s[dep] == ‘1‘ || s[dep] == ‘2‘) && (s[dep+1] >= ‘0‘ && s[dep+1] <= ‘6‘) ) numDecode(dep+2, s); } } int numDecodings(string s) { m_cnt = 0; numDecode(0, s); return m_cnt; } };
思路二:动态规划
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原文地址:http://www.cnblogs.com/diegodu/p/4378723.html