ChemliYoussef's blog

By ChemliYoussef, history, 5 years ago,

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

• -15

By ChemliYoussef, history, 5 years ago,

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?

• -6

By ChemliYoussef, history, 5 years ago,

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 ...

• +15

By ChemliYoussef, history, 5 years ago,

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

• +5

By ChemliYoussef, history, 5 years ago,

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 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()
{

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 ;
}