码迷,mamicode.com
首页 > 其他好文 > 详细

Decode Ways

时间:2015-04-02 10:26:41      阅读:127      评论:0      收藏:0      [点我收藏+]

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()];
}


 

Decode Ways

标签:dp

原文地址:http://blog.csdn.net/li_chihang/article/details/44828259

(0)
(0)
   
举报
评论 一句话评论(0
登录后才能评论!
© 2014 mamicode.com 版权所有  联系我们:gaon5@hotmail.com
迷上了代码!