Submission #419005

#	Time	Username	Problem	Language	Result	Execution time	Memory
419005		RambaXGorilla	One-Way Streets (CEOI17_oneway)	C++17	0 / 100	7 ms	9164 KiB

oneway

#include<cstdio>
#include<cstdlib>
#include<algorithm>
#include<vector>
#include<map>
#include<utility>
using namespace std;
int N, M, P;
pair <int,int> roads[100010];
pair <int,int> save[100010];
int imps[100010][3];
int dfsCnt = 0;
bool vis[100010];
int pows[20];
int dfsNums[100010];
int dfsLows[100010];
int dfsPars[100010];
int cons[100010];
int treePars[100010];
int dirs[100010];
char trans[] = {'L', 'B', 'R'};
vector <int> adjGraph[100010];
vector <int> adjTree[100010];
vector <int> adjCycles[100010];
map < pair <int,int>, int> goBack;
map < pair <int,int>, bool> bridges;
void getBridges(int u){
    dfsNums[u] = dfsLows[u] = dfsCnt++;
    for(int i = 0;i < adjGraph[u].size();i++){
        int v = adjGraph[u][i];
        if(dfsNums[v] == -1){
            dfsPars[v] = u;
            getBridges(v);
            if(dfsLows[v] > dfsNums[u]){
                bridges[make_pair(min(u, v), max(u, v))] = true;
            }
            dfsLows[u] = min(dfsLows[u], dfsLows[v]);
        }
        else if(dfsPars[u] != v || goBack[make_pair(min(u, v), max(u, v))] > 1){
            dfsLows[u] = min(dfsLows[u], dfsNums[v]);
        }      
    }
}
void getCycles(int u, int r){
    cons[u] = r;
    for(int i = 0;i < adjCycles[u].size();i++){
        int v = adjCycles[u][i];
        if(cons[v] == -1){
            getCycles(v, r);
        }
    }
}
void getTreePars(int u){
    for(int i = 0;i < adjTree[u].size();i++){
        int v = adjTree[u][i];
        if(treePars[v] == -1){
            treePars[v] = u;
            getTreePars(v);
        }
    }
}
void addTreeDirs(int u){
    vis[u] = true;
    for(int i = 0;i < adjTree[u].size();i++){
        int v = adjTree[u][i];
        if(!vis[v]){
            addTreeDirs(v);
            dirs[u] += dirs[v];
        }
    }
}
int main(){
    scanf("%d%d",&N,&M);
    for(int i = 0;i < M;i++){
        scanf("%d%d",&roads[i].first,&roads[i].second);
        save[i] = roads[i];
        if(roads[i].first > roads[i].second){
            swap(roads[i].first, roads[i].second);
        }
        else if(roads[i].first == roads[i].second){
            continue;
        }
        goBack[roads[i]] += 1;
        if(goBack[roads[i]] == 1){
            adjGraph[roads[i].first].push_back(roads[i].second);
            adjGraph[roads[i].second].push_back(roads[i].first);
        }
    }
    scanf("%d",&P);
    for(int i = 0;i < P;i++){
        scanf("%d%d",&imps[i][0],&imps[i][1]);
    }
    int length = 1;
    for(int i = 0;i < 20;i++){
        pows[i] = length;
        length *= 2;
    }
    for(int i = 0;i < 100010;i++){
        dfsNums[i] = -1;
        cons[i] = -1;
        treePars[i] = -1;
        dirs[i] = 0;
        vis[i] = false;
    }
    for(int i = 1;i < N + 1;i++){
        if(dfsNums[i] == -1){
            getBridges(i);
        }
    }
    for(int i = 0;i < M;i++){
        if(!bridges[roads[i]]){
            adjCycles[roads[i].first].push_back(roads[i].second);
            adjCycles[roads[i].second].push_back(roads[i].first);
        }
    }
    int cnt = 0;
    for(int i = 1;i < N + 1;i++){
        if(cons[i] == -1){
            cnt += 1;
            getCycles(i, cnt);
        }
    }
    for(int i = 0;i < M;i++){
        if(bridges[roads[i]]){
            adjTree[cons[roads[i].first]].push_back(cons[roads[i].second]);
            adjTree[cons[roads[i].second]].push_back(cons[roads[i].first]);
        }
    }
    for(int i = 1;i < cnt + 1;i++){
        if(treePars[i] == -1){
            treePars[i] = 0;
            getTreePars(i);
        }
    }
    for(int i = 0;i < P;i++){
        dirs[cons[imps[i][0]]] = 1;
        dirs[cons[imps[i][1]]] = -1;
    }
    for(int i = 1;i < cnt + 1;i++){
        if(!vis[i]){
            addTreeDirs(i);
        }
    }
    for(int i = 0;i < M;i++){
        int u = save[i].first;
        int v = save[i].second;
        int uT = cons[u];
        int vT = cons[v];
        if(uT == vT){
            printf("B");
            continue;
        }
        int d;
        if(treePars[uT] == vT){
            d = dirs[uT];
        }
        else{
            d = dirs[vT] * -1;
        }
        if(d != 0){
            d /= abs(d);
        }
        printf("%c",trans[d + 1]);
    }
}

Compilation message (stderr)

oneway.cpp: In function 'void getBridges(int)':
oneway.cpp:29:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   29 |     for(int i = 0;i < adjGraph[u].size();i++){
      |                   ~~^~~~~~~~~~~~~~~~~~~~
oneway.cpp: In function 'void getCycles(int, int)':
oneway.cpp:46:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   46 |     for(int i = 0;i < adjCycles[u].size();i++){
      |                   ~~^~~~~~~~~~~~~~~~~~~~~
oneway.cpp: In function 'void getTreePars(int)':
oneway.cpp:54:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   54 |     for(int i = 0;i < adjTree[u].size();i++){
      |                   ~~^~~~~~~~~~~~~~~~~~~
oneway.cpp: In function 'void addTreeDirs(int)':
oneway.cpp:64:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   64 |     for(int i = 0;i < adjTree[u].size();i++){
      |                   ~~^~~~~~~~~~~~~~~~~~~
oneway.cpp: In function 'int main()':
oneway.cpp:73:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   73 |     scanf("%d%d",&N,&M);
      |     ~~~~~^~~~~~~~~~~~~~
oneway.cpp:75:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   75 |         scanf("%d%d",&roads[i].first,&roads[i].second);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
oneway.cpp:89:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   89 |     scanf("%d",&P);
      |     ~~~~~^~~~~~~~~
oneway.cpp:91:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   91 |         scanf("%d%d",&imps[i][0],&imps[i][1]);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 30
• Subtask 2: 0 / 30
• Subtask 3: 0 / 40