# Sunday匹配算法

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## 总结：

Sunday算法比BM算法还要快。

## 一：背景

Sunday算法是Daniel M.Sunday于1990年提出的字符串模式匹配。其效率在匹配随机的字符串时比其他匹配算法还要更快。Sunday算法的实现可比KMP，BM的实现容易太多。

## 二：分析

A = “LESSONS TEARNED IN SOFTWARE TE”;
B = “SOFTWARE”;
Sunday算法的大致原理是：

## 三：完整代码

#define _CRT_SECURE_NO_DEPRECATE

#include<iostream>
#include<string>

using namespace std;

int _next[256];
string dest;
string pattern;

/*

*/
void GetNext()
{
int len = pattern.size();//get the length

for (int i = 0; i < 256; i++)
_next[i] = -1;

for (int i = 0; i < len; i++)
_next[pattern[i]] = i;
}

int SundaySearch()
{
GetNext();

int destLen = dest.size();
int patternLen = pattern.size();

if (destLen == 0) return -1;

for (int i = 0; i <= destLen - patternLen;)
{
int j = i;//dest[j]
int k = 0;//pattern[k]

for (; k<patternLen&&j < destLen&&dest[j] == pattern[k]; j++, k++)
;//do nothing

if (k == patternLen)//great! find it!
return i;
else
{
if (i + patternLen < destLen)
i += (patternLen - _next[dest[i + patternLen]]);
else
return -1;
}
}

return -1;
}

int main()
{
dest = "This is a wonderful city";

//case one(successful locating)
pattern = "wo";
int result = SundaySearch();
if (result == -1)
cout << "sorry,you do not find it!\n";
else
cout << "you find it at " << result << endl;

//case two(unsuccessful locating)
pattern = "wwe";
result = SundaySearch();
if (result == -1)
cout << "sorry,you do not find it!\n";
else
cout << "you find it at" << result << endl;

return 0;
}  

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The provided text is a code snippet and explanation of the Sunday string matching algorithm. It does not contain any mathematical questions or answers.
no_question
Given a text passage, determine:
    1. If it contains a mathematical question (including word problems or calculations)
    2. If an answer to that mathematical question is provided in the text

First, describe the content structure you found in 1-2 sentences.

Then provide your analysis in the following format:
TYPE: <one of the following values>
- NO_QUESTION
- SINGLE_QUESTION
- SINGLE_QUESTION_WITH_ANSWER
- MULTIPLE_QUESTIONS
- MULTIPLE_QUESTIONS_WITH_ANSWERS
system
# Sunday匹配算法

23 篇文章 0 订阅

## 总结：

Sunday算法比BM算法还要快。

## 一：背景

Sunday算法是Daniel M.Sunday于1990年提出的字符串模式匹配。其效率在匹配随机的字符串时比其他匹配算法还要更快。Sunday算法的实现可比KMP，BM的实现容易太多。

## 二：分析

A = “LESSONS TEARNED IN SOFTWARE TE”;
B = “SOFTWARE”;
Sunday算法的大致原理是：

## 三：完整代码

#define _CRT_SECURE_NO_DEPRECATE

#include<iostream>
#include<string>

using namespace std;

int _next[256];
string dest;
string pattern;

/*

*/
void GetNext()
{
int len = pattern.size();//get the length

for (int i = 0; i < 256; i++)
_next[i] = -1;

for (int i = 0; i < len; i++)
_next[pattern[i]] = i;
}

int SundaySearch()
{
GetNext();

int destLen = dest.size();
int patternLen = pattern.size();

if (destLen == 0) return -1;

for (int i = 0; i <= destLen - patternLen;)
{
int j = i;//dest[j]
int k = 0;//pattern[k]

for (; k<patternLen&&j < destLen&&dest[j] == pattern[k]; j++, k++)
;//do nothing

if (k == patternLen)//great! find it!
return i;
else
{
if (i + patternLen < destLen)
i += (patternLen - _next[dest[i + patternLen]]);
else
return -1;
}
}

return -1;
}

int main()
{
dest = "This is a wonderful city";

//case one(successful locating)
pattern = "wo";
int result = SundaySearch();
if (result == -1)
cout << "sorry,you do not find it!\n";
else
cout << "you find it at " << result << endl;

//case two(unsuccessful locating)
pattern = "wwe";
result = SundaySearch();
if (result == -1)
cout << "sorry,you do not find it!\n";
else
cout << "you find it at" << result << endl;

return 0;
}  

• 1
点赞
• 2
收藏
觉得还不错? 一键收藏
• 0
评论
10-17 2830
06-27 213
04-20 45
12-07 510
04-18
10-16
03-04
09-05
03-25

### “相关推荐”对你有帮助么？

• 非常没帮助
• 没帮助
• 一般
• 有帮助
• 非常有帮助

1.余额是钱包充值的虚拟货币，按照1:1的比例进行支付金额的抵扣。
2.余额无法直接购买下载，可以购买VIP、C币套餐、付费专栏及课程。
user
The provided text is a code snippet and explanation of the Sunday string matching algorithm. It does not contain any mathematical questions or answers.

TYPE: NO_QUESTION