Submission #858943

#	Time	Username	Problem	Language	Result	Execution time	Memory
858943		Tenis0206	Pipes (CEOI15_pipes)	C++11	30 / 100	1620 ms	65536 KiB

pipes

#include <bits/stdc++.h>

using namespace std;

const int nmax = 1e5;

int n,m;

int td[nmax + 5], rang[nmax + 5];

int lvl[nmax + 5], t[nmax + 5][17];

int sum[nmax + 5];

map<pair<int,int>,bool> ok;
vector<pair<int,int>> e;

vector<int> G[nmax + 5];

int rep(int x)
{
    if(x==td[x])
    {
        return x;
    }
    return (td[x] = rep(td[x]));
}

int lca(int x, int y)
{
    if(lvl[x] > lvl[y])
    {
        swap(x,y);
    }
    int dif = lvl[y] - lvl[x];
    for(int p=0; p<=16; p++)
    {
        if((dif & (1<<p))!=0)
        {
            y = t[y][p];
        }
    }
    if(x==y)
    {
        return x;
    }
    for(int p=16; p>=0; p--)
    {
        if(t[x][p] && t[y][p] && t[x][p]!=t[y][p])
        {
            x = t[x][p];
            y = t[y][p];
        }
    }
    return t[x][0];
}

void update(int x, int y)
{
    int l = lca(x,y);
    ++sum[x];
    --sum[l];
    ++sum[y];
    --sum[l];
}

void get_ans(int nod, int dad = 0)
{
    for(auto it : G[nod])
    {
        if(it==dad)
        {
            continue;
        }
        get_ans(it,nod);
        sum[nod] += sum[it];
    }
    if(sum[nod] > 0 && dad)
    {
        ok[ {nod,dad}] = true;
    }
}

void dfs_dad(int nod, int dad, int level)
{
    lvl[nod] = level;
    t[nod][0] = dad;
    for(int p=1; p<=16; p++)
    {
        t[nod][p] = t[t[nod][p-1]][p-1];
    }
    sum[nod] = 0;
    for(auto it : G[nod])
    {
        if(it==dad)
        {
            continue;
        }
        dfs_dad(it,nod,level + 1);
    }
}

int get_root(int nod)
{
    while(t[nod][0])
    {
        nod = t[nod][0];
    }
    return nod;
}

void Add(int x, int y)
{
    if(rep(x) == rep(y))
    {
        update(x,y);
        return;
    }
    e.push_back({x,y});
    int rx = rep(x);
    int ry = rep(y);
    if(rang[ry] > rang[rx])
    {
        swap(rx,ry);
        swap(x,y);
    }
    td[ry] = rx;
    rang[rx] += rang[ry];
    int r = get_root(y);
    get_ans(r);
    G[x].push_back(y);
    G[y].push_back(x);
    dfs_dad(y,x,lvl[x] + 1);
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
#ifdef home
    freopen("nr.in","r",stdin);
    freopen("nr.out","w",stdout);
#endif // home
    cin>>n>>m;
    for(int i=1;i<=n;i++)
    {
        rang[i] = 1;
        td[i] = i;
    }
    for(int i=1; i<=m; i++)
    {
        int x,y;
        cin>>x>>y;
        Add(x,y);
    }
    get_ans(get_root(1));
    for(auto it : e)
    {
        int x = it.first;
        int y = it.second;
        if(!ok[ {x,y}] && !ok[ {y,x}])
        {
            cout<<x<<' '<<y<<'\n';
        }
    }
    return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 0 / 10
• Subtask 5: 0 / 10
• Subtask 6: 0 / 10
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10
• Subtask 10: 0 / 10