C++ Programming Code Examples
C++ > Strings Code Examples
C++ Program to Implement Longest Prefix Matching
/* C++ Program to Implement Longest Prefix Matching
This C++ Program demonstrates the implementation of Longest Prefix Matching. */
#include<iostream>
#include<cstdlib>
#include<cstring>
#include<stack>
using namespace std;
/* node Declaration */
struct node
{
char data;
node *child[128];
node()
{
for (int i = 0; i < 128; i++)
child[i] = NULL;
}
};
/* trie class Declaration */
class trie
{
private:
node *root;
public:
trie()
{
root = new_node(0);
}
node *new_node(int data)
{
node *Q = new node;
Q->data = data;
return Q;
}
void add(string S)
{
node *cur = root;
for (int i = 0; i < S.length(); i++)
{
if (!cur->child[S[i] - 'A'])
cur->child[S[i] - 'A'] = new_node(S[i]);
cur = cur->child[S[i] - 'A'];
}
}
void check(node *cur, string S, int i)
{
if (cur)
{
cout<<cur->data;
if (i < S.length())
check(cur->child[S[i] - 'A'], S, i + 1);
}
}
void checkroot(string S)
{
if (root && S.length() > 0 && S[0] > 'A')
check(root->child[S[0] - 'A'],S,1);
else
cout<<"\nEmpty root \n";
}
};
/* Main */
int main()
{
trie dict;
dict.add("are");
dict.add("area");
dict.add("base");
dict.add("cat");
dict.add("cater");
dict.add("basement");
string input;
input = "caterer";
cout<<input << ": ";
dict.checkroot(input);
cout<<endl;
input = "basement";
cout<<input << ": ";
dict.checkroot(input);
cout<<endl;
input = "are";
cout<<input << ": ";
dict.checkroot(input);
cout<<endl;
input = "arex";
cout<<input << ": ";
dict.checkroot(input);
cout<<endl;
input = "basemexz";
cout<<input << ": ";
dict.checkroot(input);
cout<<endl;
input = "xyz";
cout<<input << ": ";
dict.checkroot(input);
cout<<endl;
return 0;
}
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