oj.uz

Submission #160584

# Submission time Handle Problem Language Result Execution time Memory
160584 2019-10-28T15:45:17 Z Akashi One-Way Streets (CEOI17_oneway) C++14
100 / 100
 350 ms 43124 KB 
#include <bits/stdc++.h>
using namespace std;

const int lim = 100005;

struct edge{
    int x, y;
};
edge a[lim];

int n, m, NR;
int low[lim], id[lim], h[lim], T1[lim], T2[lim];
int TT[22][lim];

char ans[lim];
bool viz[lim];

stack <int> st;
vector <pair <int, int> > v[lim];
vector <pair <int, int> > vc[lim];
vector <int> ctc[lim];

map <pair <int, int>, int> f;

void tarjan(int nod = 1, int papa = 0){
    viz[nod] = 1;
    st.push(nod);

    bool ok = 0;
    for(auto it : v[nod]){
        if(it.first == papa){
            if(!ok) ok = 1;
            else{
                low[nod] = min(low[nod], low[it.first]);
                continue ;
            }
        }
        else{
            if(viz[it.first]) low[nod] = min(low[nod], low[it.first]);
            else{
                low[it.first] = h[it.first] = h[nod] + 1;
                tarjan(it.first, nod);
                low[nod] = min(low[nod], low[it.first]);
            }
        }
    }

    if(low[nod] == h[nod]){
        int Last = 0; ++NR;
        while(Last != nod){
            Last = st.top();
            st.pop();

            ctc[NR].push_back(Last);
            id[Last] = NR;
        }
    }
}

void dfs(int nod = 1, int papa = 0){
    viz[nod] = 1;

    for(auto it : vc[nod]){
        if(papa == it.first) continue ;
        h[it.first] = h[nod] + 1;
        TT[0][it.first] = nod;
        dfs(it.first, nod);
    }
}

inline int lca(int x, int y){
    if(x == y) return h[x];

    if(h[x] < h[y]) swap(x, y);

    int p = 1, k = 0, dif = h[x] - h[y];

    while(dif > 0){
        if(dif & p){
            dif = dif ^ p;
            x = TT[k][x];
        }
        ++k; p = p << 1;
    }

    if(x == y) return h[x];

    for(int k = 20; k >= 0 ; --k)
        if(TT[k][x] != TT[k][y]) x = TT[k][x], y = TT[k][y];

    return h[x] - 1;
}

bool dir(int i, int x, int y){
    if(id[a[i].x] == x) return 1;
    return 0;
}

void solve(int nod = 1){
    viz[nod] = 1;

    for(auto it : vc[nod]){
        if(viz[it.first]) continue ;

        solve(it.first);
        T1[nod] = min(T1[nod], T1[it.first]);
        T2[nod] = min(T2[nod], T2[it.first]);

        if(ans[it.second] != NULL) continue ;

        if(T1[it.first] <= h[nod] && T2[it.first] <= h[nod]) ans[it.second] = 'B';
        else if(T1[it.first] <= h[nod]){
            if(dir(it.second, nod, it.first)) ans[it.second] = 'L';
            else ans[it.second] = 'R';
        }
        else if(T2[it.first] <= h[nod]){
            if(dir(it.second, nod, it.first)) ans[it.second] = 'R';
            else ans[it.second] = 'L';
        }
        else ans[it.second] = 'B';


    }
}

int main()
{
//    freopen("1.in", "r", stdin);

    scanf("%d%d", &n, &m);

    int x, y;
    for(int i = 1; i <= m ; ++i){
        scanf("%d%d", &x, &y);
        a[i].x = x; a[i].y = y;
        if(x == y){
            ans[i] = 'B';
            continue ;
        }

        if(f[{x, y}] > 0){
            ans[f[{x, y}]] = 'B';
            ans[i] = 'B';
            continue ;
        }

        v[x].push_back({y, i});
        v[y].push_back({x, i});
    }

    for(int i = 1; i <= n ; ++i) if(!viz[i]) tarjan(i);

    for(int i = 1; i <= NR ; ++i){
        for(auto it : ctc[i]){
            for(auto it2 : v[it]){
                if(id[it2.first] == i){
                    ans[it2.second] = 'B';
                    continue ;
                }
                vc[i].push_back({id[it2.first], it2.second});
            }
        }
    }

    memset(h, 0, sizeof(h));
    memset(viz, 0, sizeof(viz));
    for(int i = 1; i <= NR ; ++i){
        if(!viz[i]) dfs(i);
        T1[i] = h[i]; T2[i] = h[i];
    }

    for(int k = 1; k <= 20 ; ++k)
        for(int i = 1; i <= n ; ++i)
            TT[k][i] = TT[k - 1][TT[k - 1][i]];

    int t;
    scanf("%d", &t);
    while(t--){
        scanf("%d%d", &x, &y);
        if(id[x] == id[y]) continue ;
        x = id[x]; y = id[y];

        int wh = lca(x, y);
        T1[x] = min(T1[x], wh);
        T2[y] = min(T2[y], wh);
    }

    memset(viz, 0, sizeof(viz));
    for(int i = 1; i <= NR ; ++i) if(!viz[i]) solve(i);

    printf("%s", ans + 1);

    return 0;
}

Compilation message

oneway.cpp: In function 'void solve(int)':
oneway.cpp:109:30: warning: NULL used in arithmetic [-Wpointer-arith]
         if(ans[it.second] != NULL) continue ;
                              ^~~~
oneway.cpp: In function 'int main()':
oneway.cpp:130:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d", &n, &m);
     ~~~~~^~~~~~~~~~~~~~~~
oneway.cpp:134:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d", &x, &y);
         ~~~~~^~~~~~~~~~~~~~~~
oneway.cpp:177:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &t);
     ~~~~~^~~~~~~~~~
oneway.cpp:179:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d", &x, &y);
         ~~~~~^~~~~~~~~~~~~~~~

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 7932 KB Output is correct
2 Correct 11 ms 7928 KB Output is correct
3 Correct 11 ms 8188 KB Output is correct
4 Correct 10 ms 8316 KB Output is correct
5 Correct 10 ms 8336 KB Output is correct
6 Correct 10 ms 8156 KB Output is correct
7 Correct 10 ms 8440 KB Output is correct
8 Correct 10 ms 8320 KB Output is correct
9 Correct 10 ms 8184 KB Output is correct
10 Correct 10 ms 8156 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 7932 KB Output is correct
2 Correct 11 ms 7928 KB Output is correct
3 Correct 11 ms 8188 KB Output is correct
4 Correct 10 ms 8316 KB Output is correct
5 Correct 10 ms 8336 KB Output is correct
6 Correct 10 ms 8156 KB Output is correct
7 Correct 10 ms 8440 KB Output is correct
8 Correct 10 ms 8320 KB Output is correct
9 Correct 10 ms 8184 KB Output is correct
10 Correct 10 ms 8156 KB Output is correct
11 Correct 153 ms 22420 KB Output is correct
12 Correct 211 ms 24456 KB Output is correct
13 Correct 228 ms 27196 KB Output is correct
14 Correct 252 ms 31528 KB Output is correct
15 Correct 252 ms 33076 KB Output is correct
16 Correct 260 ms 36692 KB Output is correct
17 Correct 229 ms 38404 KB Output is correct
18 Correct 267 ms 36720 KB Output is correct
19 Correct 228 ms 39792 KB Output is correct
20 Correct 300 ms 25528 KB Output is correct
21 Correct 151 ms 24840 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 7932 KB Output is correct
2 Correct 11 ms 7928 KB Output is correct
3 Correct 11 ms 8188 KB Output is correct
4 Correct 10 ms 8316 KB Output is correct
5 Correct 10 ms 8336 KB Output is correct
6 Correct 10 ms 8156 KB Output is correct
7 Correct 10 ms 8440 KB Output is correct
8 Correct 10 ms 8320 KB Output is correct
9 Correct 10 ms 8184 KB Output is correct
10 Correct 10 ms 8156 KB Output is correct
11 Correct 153 ms 22420 KB Output is correct
12 Correct 211 ms 24456 KB Output is correct
13 Correct 228 ms 27196 KB Output is correct
14 Correct 252 ms 31528 KB Output is correct
15 Correct 252 ms 33076 KB Output is correct
16 Correct 260 ms 36692 KB Output is correct
17 Correct 229 ms 38404 KB Output is correct
18 Correct 267 ms 36720 KB Output is correct
19 Correct 228 ms 39792 KB Output is correct
20 Correct 300 ms 25528 KB Output is correct
21 Correct 151 ms 24840 KB Output is correct
22 Correct 350 ms 39576 KB Output is correct
23 Correct 338 ms 37652 KB Output is correct
24 Correct 349 ms 37884 KB Output is correct
25 Correct 309 ms 43124 KB Output is correct
26 Correct 308 ms 39180 KB Output is correct
27 Correct 303 ms 37752 KB Output is correct
28 Correct 78 ms 12792 KB Output is correct
29 Correct 194 ms 25976 KB Output is correct
30 Correct 194 ms 26104 KB Output is correct
31 Correct 215 ms 26632 KB Output is correct
32 Correct 213 ms 30940 KB Output is correct