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November 14th, 2017, 09:33 PM
#1
boyer moore algorithm
i am to Write a program to use Boyer Moore Algorithm to find the pattern in the string. my program can define string as “BARD LOVED BANANAS” . i need to ask user to input pattern to search. i need to display two tables. 1for good suufix shift of pattern and another to display the shift value for each step. If not match, display a message “Unsuccessful Search”. If match, display the index.
im kind of stuck with my code. any help will be appreciated
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November 15th, 2017, 05:06 AM
#2
Re: boyer moore algorithm
m kind of stuck with my code
If you post what you have, we'll be able to advise.
All advice is offered in good faith only. All my code is tested (unless stated explicitly otherwise) with the latest version of Microsoft Visual Studio (using the supported features of the latest standard) and is offered as examples only - not as production quality. I cannot offer advice regarding any other c/c++ compiler/IDE or incompatibilities with VS. You are ultimately responsible for the effects of your programs and the integrity of the machines they run on. Anything I post, code snippets, advice, etc is licensed as Public Domain https://creativecommons.org/publicdomain/zero/1.0/ and can be used without reference or acknowledgement. Also note that I only provide advice and guidance via the forums - and not via private messages!
C++23 Compiler: Microsoft VS2022 (17.6.5)
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November 15th, 2017, 09:34 AM
#3
Re: boyer moore algorithm
Code:
#include<iostream>
#include<string>
#include<algorithm>
using namespace std;
int BoyerSearch(int m,int n,string str, string pattern,int shft[]);
int main()
{
string str="BARD LOVED BANANAS";// source string
cout<<"BARD LOVED BANANAS"<<endl;
string pattern= ""; //pattern to match
cout<<"p=";
cin>>pattern;
int n=str.length();//length of the source string
int m=pattern.length();//length of the pattern string
string alphabet="";
int shft[100];//shift table
bool flag=false;
//find the alpahbets
for(int i=0;i<str.length();i++)
{
flag=false;
for(int j=0;j<alphabet.length();j++)
{
if(str.at(i)==alphabet.at(j))
flag=true;
}
if(flag!=true)
alphabet=alphabet+str.at(i);
}
std::sort(alphabet.begin(),alphabet.end());
cout<<"alphbets in the given source string: "<<alphabet<<" "<<endl;
//create shift table for the charcters occured in the pattern
for(int i=0;i<100;i++)
{
shft[i]=m;
}
for(int j=0;j<m-1;j++)
{
int t=pattern.at(j);
shft[t]=m-1-j;
}
//print shift table
cout<<"Shift table: "<<endl;
for(int j=0;j<m;j++)
{
cout<<pattern.at(j)<<" ";
}
cout<<endl<<"---------------"<<endl;
for(int j=0;j<m;j++)
{
cout<<shft[pattern.at(j)]<<" ";
}
cout<<endl;
//call for search
int k=BoyerSearch(m,n,str,pattern,shft);
if (k!=0)
cout<<"Pattern found at="<<k<<endl;
else
cout<<"Not found"<<endl;
system("pause");
return 0;
}
int BoyerSearch(int m,int n,string str, string pattern,int shft[])
{
int k=0;
while(k<=n-m)
{
int i=m-1;
while(i>=0 && str.at(k+i)==pattern.at(i))
{
i--;
}
if (i<0)
{
return k;
}
k=k+shft[str.at(k+m-1)];
}
return 0;//returns 0, if the pattern is not found
}
//that is all i have so far
Last edited by 2kaud; November 15th, 2017 at 11:37 AM.
Reason: Added code tags
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November 15th, 2017, 11:38 AM
#4
Re: boyer moore algorithm
[When posting code, please use code tags so that the code is readable. Go Advanced, select the formatted code and click '#'.]
All advice is offered in good faith only. All my code is tested (unless stated explicitly otherwise) with the latest version of Microsoft Visual Studio (using the supported features of the latest standard) and is offered as examples only - not as production quality. I cannot offer advice regarding any other c/c++ compiler/IDE or incompatibilities with VS. You are ultimately responsible for the effects of your programs and the integrity of the machines they run on. Anything I post, code snippets, advice, etc is licensed as Public Domain https://creativecommons.org/publicdomain/zero/1.0/ and can be used without reference or acknowledgement. Also note that I only provide advice and guidance via the forums - and not via private messages!
C++23 Compiler: Microsoft VS2022 (17.6.5)
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