제출 #962835

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
962835		LucaIlie	One-Way Streets (CEOI17_oneway)	C++17	100 / 100	484 ms	145984 KiB

oneway

#include <bits/stdc++.h>

using namespace std;

struct edge {
    int u, v;

    bool operator == ( const edge &x ) const {
        return (u == x.u && v == x.v) || (u == x.v && u == x.u);
    }

    bool operator != ( const edge &x ) const {
        return !(edge{ u, v } == x);
    }
};

const int none = 0;
const int up = 1;
const int down = 2;
const int MAX_N = 3e5;
const int MAX_LOG_N = 18;
const int MAX_M = 3e5;
bool vis[MAX_N + 1], isInBiconex[MAX_N + 1];
int depth[MAX_N + 1], climbDepth[MAX_N + 1], countEdges[MAX_N + 1], vertexArt[MAX_N + 1], vertexBic[MAX_N + 1], biconex[MAX_N + 1], depthArb[MAX_N + 1], parent[MAX_LOG_N + 1][MAX_N + 1], art[MAX_N + 1], dir[MAX_N + 1];
vector<int> adj[MAX_N + 1], arbAdj[MAX_N + 1];
edge edges[MAX_M];
vector<int> articulation;
vector<vector<int>> biconexe;
unordered_map<int, bool> direction[MAX_N + 1];

vector<edge> edgeStack;
unordered_map<int, int> frecvEdges[MAX_N + 1];
void findBiconexe( int u, int p ) {
    vis[u] = true;
    depth[u] = depth[p] + 1;
    climbDepth[u] = depth[u];
    int c = 0;
    for ( int v: adj[u] ) {
        if ( v == p )
            continue;

        if ( vis[v] ) {
            if ( depth[v] < depth[u] ) {
                edgeStack.push_back( { u, v } );
                climbDepth[u] = min( climbDepth[u], depth[v] );
            }
        } else {
            edgeStack.push_back( { u, v } );
            c++;
            findBiconexe( v, u );
            climbDepth[u] =min( climbDepth[u], climbDepth[v] );

            if ( climbDepth[v] >= depth[u] ) {
                biconexe.push_back( {} );
                if ( p != 0 )
                    articulation.push_back( u );

                edge e;
                do {
                    e = edgeStack.back();
                    edgeStack.pop_back();
                    countEdges[biconexe.size() - 1] += frecvEdges[e.u][e.v] + frecvEdges[e.v][e.u];
                    if ( !isInBiconex[e.u] ) {
                        biconexe.back().push_back( e.u );
                        isInBiconex[e.u] = true;
                    }
                    if ( !isInBiconex[e.v] ) {
                        biconexe.back().push_back( e.v );
                        isInBiconex[e.v] = true;
                    }
                } while ( e != edge{ u, v } );

                for ( int w: biconexe.back() )
                    isInBiconex[w] = false;
            }
        }
    }

    if ( p == 0 && c > 1 )
        articulation.push_back( u );
}

void dfs( int u, int p ) {
    vis[u] = true;
    parent[0][u] = p;
    depthArb[u] = depthArb[p] + 1;
    for ( int v: arbAdj[u] ) {
        if ( v == p )
            continue;
        dfs( v, u );
    }
}

void initLca( int n ) {
    for ( int p = 1; p <= MAX_LOG_N; p++ ) {
        for ( int v = 1; v <= n; v++ )
            parent[p][v] = parent[p - 1][parent[p - 1][v]];
    }
}

int lca( int u, int v ) {
    if ( depthArb[u] > depthArb[v] )
        swap( u, v );

    for ( int p = MAX_LOG_N; p >= 0; p-- ) {
        if ( depthArb[parent[p][v]] >= depthArb[u] )
            v = parent[p][v];
    }


    if ( u == v )
        return u;

    for ( int p = MAX_LOG_N; p >= 0; p-- ) {
        if ( parent[p][u] != parent[p][v] ) {
            u = parent[p][u];
            v = parent[p][v];
        }
    }

    return parent[0][u];
}

int updateUp[MAX_N + 1], dpUp[MAX_N + 1], updateDown[MAX_N + 1], dpDown[MAX_N + 1];
void calcUpDown( int u, int p ) {
    vis[u] = true;
    dpUp[u] = updateUp[u];
    dpDown[u] = updateDown[u];
    for ( int v: arbAdj[u] ) {
        if ( v == p )
            continue;
        calcUpDown( v, u );
        dpUp[u] += dpUp[v];
        dpDown[u] += dpDown[v];
    }
    if ( dpUp[u] > 0 )
        dir[u] = up;
    if ( dpDown[u] > 0 )
        dir[u] = down;

    //printf( "%d %d %d\n", u, dpDown[u], dpUp[u] );
}

int main() {
    int n, m;

    cin >> n >> m;
    for  ( int i = 0; i < m; i++ ) {
        int u, v;
        cin >> u >> v;
        edges[i] = { u, v };
        if ( u == v )
            continue;

        adj[u].push_back( v );
        adj[v].push_back( u );
        if ( u > v )
            swap( u, v );
        frecvEdges[u][v]++;
    }

    for ( int v = 1; v <= n; v++ ) {
        if ( !vis[v] )
            findBiconexe( v, 0 );
    }

    /*int i = 0;
    for ( vector<int> b: biconexe ) {
        for ( int v: b )
            cout << v << " ";
        cout << "\n";
        cout << countEdges[i++] << "\n";
    }
    for ( int v: articulation )
        cout << v << " ";
    cout << "\n";*/

    int vert = 0;
    for ( int v: articulation ) {
        vertexArt[v] = ++vert;
        art[vert] = v;
    }
    for ( int i = 0; i < biconexe.size(); i++ ) {
        vertexBic[i] = ++vert;
        for ( int v: biconexe[i] ) {
            if ( vertexArt[v] ) {
                arbAdj[vertexArt[v]].push_back( vertexBic[i] );
                arbAdj[vertexBic[i]].push_back( vertexArt[v] );
                //printf( "edgearb %d %d %d %d\n", v, i, vertexArt[v], vertexBic[i] );
            } else
                biconex[v] = i;
        }
    }

    for ( int v = 1; v <= n; v++ )
        vis[v] = false;
    for ( int v = 1; v <= n; v++ ) {
        if ( !vis[v] )
            dfs( v, 0 );
    }

    initLca( vert );
    for ( int v = 1; v <= vert; v++ )
        dir[v] = none;

    int k;
    cin >> k;
    for ( int i = 0; i < k; i++ ) {
        int u, v;
        cin >> u >> v;
        int a = u, b = v;

        u = (vertexArt[u] ? vertexArt[u] : vertexBic[biconex[u]]);
        v = (vertexArt[v] ? vertexArt[v] : vertexBic[biconex[v]]);
        int l = lca( u, v );
        //printf( "%d %d %d\n", u, v,  l );
        //printf( "%d %d\n", u, v );

        if ( u == v && countEdges[u - 1 - articulation.size()] == 1 )
            direction[a][b] = 1;

        if ( k <= 100 ) {
            while ( depthArb[u] > depthArb[v] ) {
                if ( u > articulation.size() )
                    dir[u] = up;
                //printf( "%d\n", u );
                u = parent[0][u];
            }
            while ( depthArb[v] > depthArb[u] ) {
                if ( v > articulation.size() )
                    dir[v] = down;
                // printf( "%d\n", v );
                v = parent[0][v];
            }
            while ( u != v ) {
                //printf( "%d\n%d\n", u, v );
                if ( u > articulation.size())
                    dir[u] = up;
                u = parent[0][u];
                if ( v > articulation.size())
                    dir[v] = down;
                v = parent[0][v];
            }
        } else {
            updateUp[u]++;
            updateUp[parent[0][l]]--;
            updateDown[v]++;
            updateDown[parent[0][l]]--;
        }
    }

    for ( int v = 1; v <= n; v++ )
        vis[v] = false;
    for ( int v = 1; v <= n; v++ ) {
        if ( !vis[v] )
            calcUpDown( v, 0 );
    }

    for ( int i = 0; i < biconexe.size(); i++ ) {
        int v = vertexBic[i];
        if ( countEdges[i] != 1 )
            continue;

        int a = biconexe[i][0], b = biconexe[i][1];
        //printf( "ba %d %d %d\n", v, a, b );
        if ( a == art[parent[0][v]] )
            swap( a, b );

        if ( dir[v] == up )
            direction[a][b] = 1;
        else if ( dir[v] == down )
            direction[b][a] = 1;
    }

    string ans = "";
    for ( int i = 0; i < m; i++ ) {
        int u = edges[i].u, v = edges[i].v;
        if ( direction[u][v] )
            ans += 'R';
        else if ( direction[v][u] )
            ans += 'L';
        else
            ans += 'B';
        //cout << i << " " << ans.back() << "\n";
    }

    cout << ans;

    return 0;
}

컴파일 시 표준 에러 (stderr) 메시지

oneway.cpp: In function 'int main()':
oneway.cpp:183:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  183 |     for ( int i = 0; i < biconexe.size(); i++ ) {
      |                      ~~^~~~~~~~~~~~~~~~~
oneway.cpp:224:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  224 |                 if ( u > articulation.size() )
      |                      ~~^~~~~~~~~~~~~~~~~~~~~
oneway.cpp:230:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  230 |                 if ( v > articulation.size() )
      |                      ~~^~~~~~~~~~~~~~~~~~~~~
oneway.cpp:237:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  237 |                 if ( u > articulation.size())
      |                      ~~^~~~~~~~~~~~~~~~~~~~~
oneway.cpp:240:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  240 |                 if ( v > articulation.size())
      |                      ~~^~~~~~~~~~~~~~~~~~~~~
oneway.cpp:259:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  259 |     for ( int i = 0; i < biconexe.size(); i++ ) {
      |                      ~~^~~~~~~~~~~~~~~~~

• Subtask 1: 30 / 30
• Subtask 2: 30 / 30
• Subtask 3: 40 / 40