ChemliYoussef's blog

By ChemliYoussef, history, 5 years ago, In English

Hi everybody, i want to know if there is a way to see code submitted during past srms ? thanks in advance ...

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By ChemliYoussef, history, 5 years ago, In English

Hello everyone .
Is there anyone who can explain to me the 5th method of resolution of LCA mentioned on amd's blog ? I did not understand the relation between A' and B and P and how to fill Table P.
I did not understand also the advantage of making A a binary sequence?
I know this is very simple for most of you but I have already some days stuck and the topcoder tutorial is the same as that of amd ...
About tarjan's algorithm, is it necessary to know what is a Akermann function?
Thanks in advance ...

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By ChemliYoussef, history, 5 years ago, In English

Hi everyone , I wanted to learn aho — Corasick algorithm but the problem that the tutorials found on google are not detailed ...
For example I want to know why we look for the suffix -link of each node and how this algorithm works ...

thanks in advance

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By ChemliYoussef, history, 5 years ago, In English

hello everyone , I want to know if a tree has a single centroid because I encounter some cases where I find 2 centroids...
thanks in advance ...

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By ChemliYoussef, history, 5 years ago, In English

Hi everyone ... I don't why my BridgeFinding code gives a wrong anwser for graph :
6 7 -- > n , m
1 2 -- > edge : u -- v
2 3
1 3
3 4
4 6
4 6
4 5
The problem that i don't know why it takes edge 4 -- 6 as a bridge
code :

#include<bits/stdc++.h>

#define read_fast ios_base::sync_with_stdio(0) , cin.tie(0)
#define ll long long int 
#define pb push_back
#define mp make_pair

using namespace std ;

int n , m , dfs_Count ;
int dfs_num [ 1010 ] , dfs_low [ 1010 ] , dfs_par [ 1010 ] ;
vector < int  > adj [ 1010 ] ; 

void Bridge ( int u ) 
{
    dfs_low [ u ] = dfs_num [ u ] = ++ dfs_Count ; 
    for ( int i = 0 ; i < adj [ u ] . size() ; i ++ )
    {
        int j = adj [ u ][ i ]  ; 
        if ( ! dfs_num [ j ] )
        {
            dfs_par [ j ] = u ;
            
            Bridge ( j ) ;
            
            if ( dfs_low [ j ] > dfs_num [ u ] )
            { 
                cout << u << " " << j << '\n' ; 
            }
            dfs_low [ u ] = min ( dfs_low [ u ] , dfs_low [ j ] ) ;
        }
        else if ( j != dfs_par [ u ] )
            dfs_low [ u ] = min ( dfs_low [ u ] , dfs_num [ j ] ) ;
    }
    
    return ;
}

int main()
{
    read_fast ;
    
    cin >> n >> m ;
    for ( int i = 0 ; i < m ; i ++ )
    { 
        int a , b ;
        cin >> a >> b ;
        adj [ a ] . pb ( b ) ;
        adj [ b ] . pb ( a ) ;
    }
    
    Bridge ( 1 ) ;
    
    return 0 ;
}

Thanks in advance

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