Cod sursa(job #1662902)

Utilizator bogdanboboc97Bogdan Boboc bogdanboboc97 Data 25 martie 2016 11:35:08
Problema Radiatie Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 2.89 kb
#include <iostream>
#include <vector>
#include <algorithm>
#include <limits>
#include <numeric>
#include <cstring>
#include <string>
#include <queue>
#include <set>
#include <cmath>
#include <fstream>
#include <cstdlib>
#include <map>
#define pb push_back
#define mp make_pair
#define INF numeric_limits<int>::max()
#define bit(x) (-x)&x
using namespace std;
ifstream in("radiatie.in");
ofstream out("radiatie.out");
pair< int , pair<int,int> > edge[30002];
vector<int> c;
vector< vector< pair<int,int > > > a;
int n,m,tcost;
int group(int i)
{
    if(i==c[i])return i;
    c[i]=group(c[i]);
    return c[i];
}
void unite(int i,int j)
{
    c[group(i)]=group(j);
}
void Kruskal()
{
    for(int i=1;i<=n;i++)
        c[i]=i;
    for(int i=1,step=0;i<=m && step!=n-1;i++)
    if(group(edge[i].second.first) != group(edge[i].second.second))
    {
        unite(edge[i].second.first,edge[i].second.second);
        a[ edge[i].second.first ].pb( mp(edge[i].second.second,edge[i].first) );
        a[ edge[i].second.second ].pb( mp(edge[i].second.first,edge[i].first) );
        step++;
    }
}
vector<int> p,eul,lvl;
int k,dp[15][30000],str[15][30000],dist[30000];
void dfs(int x,int level,int f)
{
    lvl[++k]=level;
    eul[k]=x;
    p[x]=k;
    for(vector< pair<int,int> >::iterator i=a[x].begin();i!=a[x].end();i++)
    if(p[i->first]==0)
    {
        dist[i->first]=dist[x]+1;
        dp[0][i->first]=i->second;
        str[0][i->first]=x;
        dfs(i->first,level+1,x);
        lvl[++k]=level;
        eul[k]=x;
    }
}
int RMQ[17][100000],lg[100000];
void rmq()
{
    for(int i=1;i<=k;i++)
    {
        if(i>=2)
            lg[i]=lg[i/2]+1;
        RMQ[0][i]=i;
    }
    for(int i=1;(1<<i)<=k;i++)
    for(int j=1;j<=k-(1<<i)+1;j++)
        RMQ[i][j]=( lvl[ RMQ[i-1][j] ] > lvl[ RMQ[i-1][j+(1<<(i-1))] ] ? RMQ[i-1][j+(1<<(i-1))] : RMQ[i-1][j] );
}
int LCA(int x,int y)
{
    x=p[x];
    y=p[y];
    if(x>y)
        swap(x,y);
    int diff=y-x+1;
    return (lvl[ RMQ[lg[diff]][x] ]  > lvl[ RMQ[lg[diff]][x+diff-(1<<lg[diff])] ] ? eul[ RMQ[lg[diff]][x+diff-(1<<lg[diff])] ] : eul[ RMQ[lg[diff]][x] ]);
}
int query(int x,int k)
{
    if(k>0)
        return max(dp[lg[k]][x],query(str[lg[k]][x],k-(1<<lg[k])));
else return 0;
}
int solve(int x,int y)
{
    int z=LCA(x,y);
    return max(query(x,dist[x]-dist[z]),query(y,dist[y]-dist[z]));
}
int main()
{
    int q;
    in>>n>>m>>q;
    a=vector< vector< pair<int,int> > > (n+1);
    p=vector<int> (n+1);
    lvl=eul=vector<int> (2*n+2);
    for(int i=1;i<=m;i++)
        in>>edge[i].second.first>>edge[i].second.second>>edge[i].first;
    c=vector<int> (n+1);
    sort(edge+1,edge+m+1);
    Kruskal();
    dfs(1,1,1);
    rmq();
    for(int i=1;(1<<i)<=n;i++)
    for(int j=1;j<=n;j++)
    {
        str[i][j]=str[i-1][ str[i-1][j] ];
        dp[i][j]=max(dp[i-1][ str[i-1][j] ],dp[i-1][j]);
    }
    for(;q;q--)
    {
        int x,y;
        in>>x>>y;
        out<<solve(x,y)<<'\n';
    }
    return 0;
}