Submission #153163

#	Time	Username	Problem	Language	Result	Execution time	Memory
153163		Mercenary	Pipes (CEOI15_pipes)	C++14	50 / 100	5073 ms	46240 KiB

pipes

#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/trie_policy.hpp>

#define pb push_back
#define mp make_pair
#define taskname "A"

using namespace std;
using namespace __gnu_pbds;

typedef long long ll;
typedef long double ld;
typedef pair<int,int> ii;
typedef tree <int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update> ordered_set;

const int maxn = 1e5 + 5;
const int logn = log2(maxn) + 1;
int n , m , nEdge = 0;

struct Edge{
    int u , v;
    bool col;
}e[maxn];

int par[maxn] , P[maxn][logn];
int lab[maxn] , h[maxn] , dp[maxn];
vector<int> adj[maxn];

int FindLab(int u){
    return lab[u] < 0 ? u : lab[u] = FindLab(lab[u]);
}

void BuildLCA(int u , int par){
    P[u][0] = par;
    for(int i = 1 ; i < logn && P[u][i - 1] ; ++i){
        P[u][i] = P[P[u][i - 1]][i - 1];
    }
}

void dfs(int u , int par){
    for(int c : adj[u]){
        if(par != e[c].u + e[c].v - u){
            h[e[c].u + e[c].v - u] = h[u] + 1;
            ::par[e[c].u + e[c].v - u] = c;
            BuildLCA(e[c].u + e[c].v - u , u);
            dfs(e[c].u + e[c].v - u , u);
        }
    }
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    if(fopen(taskname".INP","r")){
		freopen(taskname".INP", "r",stdin);
		freopen(taskname".OUT", "w",stdout);
    }
    fill_n(lab,maxn,-1);
    fill_n(par,maxn,-1);

    cin >> n >> m;
    for(int i = 1 ; i <= m ; ++i){
        int u , v;cin >> u >> v;
        int s , t;
        s = FindLab(u);
        t = FindLab(v);
        if(s != t){
            e[nEdge].u = u;e[nEdge].v = v;
            if(lab[s] > lab[t])swap(s , t) , swap(u , v);
            lab[s] += lab[t];
            lab[t] = s;
            adj[u].pb(nEdge);
            adj[v].pb(nEdge);
            ++nEdge;
        }
    }
    for(int i = 1 ; i <= n ; ++i){
        if(h[i] == 0){
            dfs(i , 0);
        }
    }
    fill_n(lab,maxn,-1);
    rewind(stdin);
    cin >> n >> m;
    for(int i = 1 ; i <= m ; ++i){
        int u , v;cin >> u >> v;
        int s , t;
        s = FindLab(u);
        t = FindLab(v);
        if(s != t){
            if(lab[s] > lab[t])swap(s , t) , swap(u , v);
            lab[s] += lab[t];
            lab[t] = s;
        }else{
            auto lca = [&](int u , int v){
                if(h[u] < h[v])swap(u , v);
                for(int i = 0 ; i < logn ; ++i){
                    if((h[u] - h[v]) & (1 << i))u = P[u][i];
                }
                if(u == v)return u;
                for(int i = logn - 1 ; i >= 0 ; --i){
                    if(P[u][i] != P[v][i])u = P[u][i] , v = P[v][i];
                }
                return P[u][0];
            };
            dp[u]++;dp[v]++;
            dp[lca(u,v)] -= 2;
        }
    }
    fill_n(h,maxn,0);
    for(int i = 1 ; i <= n ; ++i){
        if(h[i] == 0){
            function<void(int,int)> dfs = [&](int u , int par){
                for(int c : adj[u]){
                    int v = e[c].u + e[c].v - u;
                    if(v != par){
                        h[v] = h[u] + 1;
                        dfs(v , u);
                        dp[u] += dp[v];
                    }
                }
                if(dp[u] > 0)e[::par[u]].col = 1;
            };
            dfs(i , 0);
        }
    }
    for(int i = 0 ; i < nEdge ; ++i){
        if(e[i].col == 0)cout << e[i].u << " " << e[i].v << endl;
    }
}

Compilation message (stderr)

pipes.cpp: In function 'int main()':
pipes.cpp:57:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   freopen(taskname".INP", "r",stdin);
   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
pipes.cpp:58:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   freopen(taskname".OUT", "w",stdout);
   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~

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