Cod sursa(job #3207015)

Utilizator matei__bBenchea Matei matei__b Data 24 februarie 2024 18:29:18
Problema Radiatie Scor 100
Compilator cpp-64 Status done
Runda Arhiva de probleme Marime 2.85 kb
#include <bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define ld long double
#define chad char
#define mod 666013
#define dim 100005
#define lim 1000000
#define INF 1000000000
#define FOR(i,a,b) for(int i=(a); i<=(b); i++)
#define piii pair<int,pair<int,int> > 
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pb push_back
#define mp make_pair
#define nr_biti __builtin_popcount
using namespace std;
 
ifstream fin("radiatie.in");
ofstream fout("radiatie.out"); 

int n,m,k;

struct muchie 
{
    int x,y,w;

    bool operator<(const muchie &other)
    {
        return w<other.w; 
    }
}v[dim];

int t[dim];
vector<pii> g[dim];

int root(int nod)
{
    if(nod==t[nod])
        return nod;

    return t[nod]=root(t[nod]);
}

bool unite(int x,int y)
{
    x=root(x);
    y=root(y);

    if(x==y)
        return 0;

    t[y]=x;

    return 1;
}

int c[30][dim];
int st[30][dim];
int h[dim];

void dfs(int nod,int daddy=0)
{
    t[nod]=daddy;
    st[0][nod]=daddy;
    h[nod]=1+h[daddy];
    
    for(auto it:g[nod])
    {
        if(it.first==daddy)
            continue;
        
        c[0][it.first]=it.second;
        dfs(it.first,nod);
    }
}

void pre()
{
    for(int i=1; (1<<i)<=n; i++)
        for(int j=1; j<=n; j++) 
        {
            st[i][j]=st[i-1][st[i-1][j]];
            c[i][j]=max(c[i-1][j],c[i-1][st[i-1][j]]);
        }
}

int bl(int nod,int niv)
{
    int z=0;

    while(niv)
    {
        if(niv&1)
            nod=st[z][nod];

        z++;
        niv/=2;
    }

    return nod;
}

int lca(int x,int y)
{
    if(h[x]>h[y])
        swap(x,y);

    int dif=h[y]-h[x];

    y=bl(y,dif);

    if(x==y)
        return x;

    for(int i=20; i>=0; i--)
    {
        if(st[i][x]!=st[i][y])
        {
            x=st[i][x];
            y=st[i][y];
        }
    }

    return st[0][x];
}

int solve(int nod,int niv)
{
    int ans=0;
    int z=0;

    while(niv)
    {
        if(niv&1)
        {
            ans=max(ans,c[z][nod]);
            nod=st[z][nod];
        }

        z++;
        niv/=2;
    }

    return ans;
}

int main()
{
    ios_base::sync_with_stdio(false);
    fin.tie(nullptr);
    fout.tie(nullptr); 

    fin >> n >> m >> k;

    for(int i=1; i<=m; i++)
        fin >> v[i].x >> v[i].y >> v[i].w;

    sort(v+1,v+1+m);

    for(int i=1; i<=n; i++)
        t[i]=i;

    for(int i=1; i<=m; i++)
    {
        if(unite(v[i].x,v[i].y))
        {
            g[v[i].x].pb(mp(v[i].y,v[i].w));
            g[v[i].y].pb(mp(v[i].x,v[i].w));
        }
    }

    dfs(1);
    pre();

    while(k--)
    {
        int x,y,u;

        fin >> x >> y;

        u=lca(x,y);

        fout << max(solve(x,h[x]-h[u]),solve(y,h[y]-h[u])) << "\n";
    }

    return 0;
}