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Submission #910091

# Submission time Handle Problem Language Result Execution time Memory
910091 2024-01-17T21:41:39 Z asdasdqwer Pipes (CEOI15_pipes) C++14
70 / 100
 778 ms 18652 KB 
#include <bits/stdc++.h>
using namespace std;

struct DSU {
    vector<int> p,r;
    DSU(int n) : p(n),r(n,1) {
        for (int i=0;i<n;i++)p[i]=i;
    }

    int get(int i) {
        if (p[i]!=i && p[i]!=p[p[i]]) p[i]=get(p[i]);
        return p[i];
    }

    bool unite(int a,int b) {
        a=get(a),b=get(b);
        if (a==b)return false;
        if (r[a]<r[b])swap(a,b);
        p[b]=a;
        r[a]+=r[b];
        return true;
    }
};


vector<int> st(1e5+1, 0);

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    int n,m;cin>>n>>m;
    DSU d1(n), d2(n);
    vector<vector<int>> g(n);

    for (int i=0;i<m;i++) {
        int a,b;cin>>a>>b;a--;b--;
        if (d1.unite(a,b)) {
            g[a].push_back(b);
            g[b].push_back(a);
        }

        else {
            d2.unite(a,b);
        }
    }

    d1.r.clear();
    d2.r.clear();

    vector<vector<int>> lft(n, vector<int>(18, -1));
    bitset<100001> vis;
    vector<int> d(n,0);

    for (int i=0;i<n;i++) {
        if (vis[i]) continue;
        int pt=0;
        st[pt]=i;
        vis[i]=true;
        while (pt != -1) {
            int r=st[pt--];
            for (int x:g[r]) {
                if (!vis[x]) {
                    vis[x]=true;
                    lft[x][0]=r;
                    d[x]=d[r]+1;
                    st[++pt]=x;
                }
            }
        }
    }

    for (int j=1;j<18;j++) {
        for (int i=0;i<n;i++) {
            lft[i][j]=lft[i][j-1];
            if (lft[i][j] != -1) {
                lft[i][j]=lft[lft[i][j]][j-1];
            }
        }
    }

    vector<int> dp(n, 0);

    for (int i=0;i<n;i++) {
        if (d2.p[i] == i) continue;
        int a=i, b=d2.get(i);
        dp[a]++;
        dp[b]++;

        if (d[a]<d[b])swap(a,b);
        int steps=d[a]-d[b];
        int cnt=0;
        while (steps) {
            if ((steps&1)==1) {
                a=lft[a][cnt];
            }
            steps>>=1;cnt++;
        }
        
        if (a==b) {
            dp[a]-=2;
            continue;
        }

        for (int i=17;i>-1;--i) {
            if (lft[a][i] != lft[b][i]) {
                a=lft[a][i];
                b=lft[b][i];
            }
        }

        dp[lft[a][0]] -= 2;
    }

    for (int i=0;i<n;i++) vis[i]=0;
    
    function<void(int)> dfs2=[&](int node) {
        vis[node]=true;
        for (int x:g[node]) {
            if (vis[x])continue;
            dfs2(x);
            dp[node]+=dp[x];
        }
    };

    for (int i=0;i<n;i++) {
        st[i]=-1;
    }

    for (int i=0;i<n;i++) {
        if (vis[i])continue;
        int pt=0;
        vis[i]=true;
        st[0]=i;
        while (pt != -1) {
            int r=st[pt];
            for (int x:g[r]) {
                if (!vis[x]) {
                    st[++pt]=x;
                    vis[x]=true;
                }
            }

            if (r == st[pt]) {
                if (lft[r][0] != -1) {
                    dp[lft[r][0]] += dp[r];
                }

                st[pt]=-1;
                
                pt--;
            }
        }
    }

    for (int i=0;i<n;i++) {
        if (dp[i]==0 && lft[i][0] != -1) {
            cout<<i+1<<" "<<lft[i][0]+1<<"\n";
        }
    }

    return 0;
}

Subtask #1
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 860 KB Output is correct
2 Correct 1 ms 860 KB Output is correct

Subtask #2
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 1628 KB Output is correct
2 Correct 4 ms 1628 KB Output is correct

Subtask #3
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 64 ms 1364 KB Output is correct
2 Correct 67 ms 1360 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 117 ms 2552 KB Output is correct
2 Correct 129 ms 2296 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 193 ms 5076 KB Output is correct
2 Correct 165 ms 5968 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 307 ms 13608 KB Output is correct
2 Correct 245 ms 13396 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 412 ms 15308 KB Output is correct
2 Correct 437 ms 15188 KB Output is correct

Subtask #8
0 / 10.0

# Verdict Execution time Memory Grader output
1 Runtime error 573 ms 18600 KB Memory limit exceeded
2 Halted 0 ms 0 KB -

Subtask #9
0 / 10.0

# Verdict Execution time Memory Grader output
1 Runtime error 661 ms 18652 KB Memory limit exceeded
2 Halted 0 ms 0 KB -

Subtask #10
0 / 10.0

# Verdict Execution time Memory Grader output
1 Runtime error 778 ms 17740 KB Memory limit exceeded
2 Halted 0 ms 0 KB -