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Submission #320680

# Submission time Handle Problem Language Result Execution time Memory
320680 2020-11-09T13:53:53 Z phathnv One-Way Streets (CEOI17_oneway) C++11
100 / 100
 126 ms 23780 KB 
#include <bits/stdc++.h>

using namespace std;

#define X first
#define Y second
#define mp make_pair

typedef long long ll;
typedef pair <int, int> ii;

const int N = 1e5 + 1;
const int logN = 17;

struct edge{
    int u, v;
    edge(int _u = 0, int _v = 0){
        u = _u;
        v = _v;
    }
};

struct dsu{
    int root[N], rnk[N];
    void reset(int n){
        for(int i = 1; i <= n; i++){
            root[i] = i;
            rnk[i] = 0;
        }
    }
    int getRoot(int u){
        if (u == root[u])
            return u;
        root[u] = getRoot(root[u]);
        return root[u];
    }
    bool unite(int u, int v){
        u = getRoot(u);
        v = getRoot(v);
        if (u == v)
            return 0;
        if (rnk[u] < rnk[v])
            swap(u, v);
        root[v] = u;
        rnk[u] += (rnk[u] == rnk[v]);
        return 1;
    }
} G;

int n, m, p;
edge e[N];

bool used[N];
vector <ii> adj[N];
int h[N], par[N][logN], edgeToPar[N], cnt[N], dir[N];
char ans[N];


int inComp[N], nComp;

void readInput(){
    scanf("%d %d", &n, &m);
    for(int i = 1; i <= m; i++)
        scanf("%d %d", &e[i].u, &e[i].v);
}

void dfs(int u, int p){

    inComp[u] = nComp;

    for(int i = 1; i < logN; i++)
        par[u][i] = par[par[u][i - 1]][i - 1];
    for(ii e : adj[u]){
        int v = e.X;
        int id = e.Y;
        if (v != p){
            h[v] = h[u] + 1;
            par[v][0] = u;
            edgeToPar[v] = id;
            dfs(v, u);
        }
    }
}

int getLCA(int u, int v){
    if (h[u] > h[v])
        swap(u, v);
    for(int i = logN - 1; i >= 0; i--)
        if (h[u] <= h[v] - (1 << i))
            v = par[v][i];
    if (u == v)
        return u;
    for(int i = logN - 1; i >= 0; i--)
        if (par[u][i] != par[v][i]){
            u = par[u][i];
            v = par[v][i];
        }
    return par[u][0];
}

void slowMarkNotCutEdge(int u, int v){
    while (u != v){
        if (h[u] > h[v])
            swap(u, v);
        cnt[v]++;
        v = par[v][0];
    }
}

void slowMarkDir(int u, int v){
    while (u != v){
        if (h[u] > h[v]){
            dir[u]--;
            u = par[u][0];
        } else {
            dir[v]++;
            v = par[v][0];
        }
    }
}

void markNotCutEdge(int u, int v){
    int lca = getLCA(u, v);
    cnt[u]++;
    cnt[v]++;
    cnt[lca] -= 2;
}

void markDir(int u, int v){
    dir[u]--;
    dir[v]++;
}

void dfs2(int u, int p){
    for(ii e : adj[u]){
        int v = e.X;
        if (v != p){
            dfs2(v, u);
            cnt[u] += cnt[v];
            dir[u] += dir[v];
        }
    }
}

void prepare(){
    G.reset(n);
    for(int i = 1; i <= m; i++)
        if (G.unite(e[i].u, e[i].v)){
            used[i] = 1;
            adj[e[i].u].push_back(mp(e[i].v, i));
            adj[e[i].v].push_back(mp(e[i].u, i));
        }
    for(int i = 1; i <= n; i++)
        if (!par[i][0]){
            ++nComp;
            dfs(i, -1);
        }
    for(int i = 1; i <= m; i++)
        if (!used[i])
            markNotCutEdge(e[i].u, e[i].v);
}

void solve(){
    scanf("%d", &p);
    for(int i = 1; i <= p; i++){
        int u, v;
        scanf("%d %d", &u, &v);
        markDir(u, v);
    }
    memset(ans, 'B', sizeof(ans));

    for(int i = 1; i <= n; i++)
        if (par[i][0] == 0)
            dfs2(i, -1);

    for(int i = 1; i <= n; i++)
        if (par[i][0]){
            if (cnt[i] > 0 || dir[i] == 0)
                continue;
            int id = edgeToPar[i];
            if (dir[i] < 0)
                ans[id] = (e[id].u == i? 'R' : 'L');
            else
                ans[id] = (e[id].u == i? 'L' : 'R');
        }

    for(int i = 1; i <= m; i++)
        putchar(ans[i]);
}

int main(){
    readInput();
    prepare();
    solve();
    return 0;
}

Compilation message

oneway.cpp: In function 'void readInput()':
oneway.cpp:62:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   62 |     scanf("%d %d", &n, &m);
      |     ~~~~~^~~~~~~~~~~~~~~~~
oneway.cpp:64:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   64 |         scanf("%d %d", &e[i].u, &e[i].v);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
oneway.cpp: In function 'void solve()':
oneway.cpp:164:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  164 |     scanf("%d", &p);
      |     ~~~~~^~~~~~~~~~
oneway.cpp:167:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  167 |         scanf("%d %d", &u, &v);
      |         ~~~~~^~~~~~~~~~~~~~~~~

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 3564 KB Output is correct
2 Correct 3 ms 3564 KB Output is correct
3 Correct 3 ms 3692 KB Output is correct
4 Correct 3 ms 3692 KB Output is correct
5 Correct 3 ms 3820 KB Output is correct
6 Correct 3 ms 3692 KB Output is correct
7 Correct 3 ms 3820 KB Output is correct
8 Correct 3 ms 3692 KB Output is correct
9 Correct 3 ms 3692 KB Output is correct
10 Correct 3 ms 3692 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 3564 KB Output is correct
2 Correct 3 ms 3564 KB Output is correct
3 Correct 3 ms 3692 KB Output is correct
4 Correct 3 ms 3692 KB Output is correct
5 Correct 3 ms 3820 KB Output is correct
6 Correct 3 ms 3692 KB Output is correct
7 Correct 3 ms 3820 KB Output is correct
8 Correct 3 ms 3692 KB Output is correct
9 Correct 3 ms 3692 KB Output is correct
10 Correct 3 ms 3692 KB Output is correct
11 Correct 56 ms 7268 KB Output is correct
12 Correct 55 ms 8804 KB Output is correct
13 Correct 68 ms 11364 KB Output is correct
14 Correct 91 ms 15072 KB Output is correct
15 Correct 98 ms 16228 KB Output is correct
16 Correct 103 ms 18020 KB Output is correct
17 Correct 98 ms 19560 KB Output is correct
18 Correct 103 ms 18008 KB Output is correct
19 Correct 98 ms 20708 KB Output is correct
20 Correct 74 ms 11492 KB Output is correct
21 Correct 57 ms 11748 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 3564 KB Output is correct
2 Correct 3 ms 3564 KB Output is correct
3 Correct 3 ms 3692 KB Output is correct
4 Correct 3 ms 3692 KB Output is correct
5 Correct 3 ms 3820 KB Output is correct
6 Correct 3 ms 3692 KB Output is correct
7 Correct 3 ms 3820 KB Output is correct
8 Correct 3 ms 3692 KB Output is correct
9 Correct 3 ms 3692 KB Output is correct
10 Correct 3 ms 3692 KB Output is correct
11 Correct 56 ms 7268 KB Output is correct
12 Correct 55 ms 8804 KB Output is correct
13 Correct 68 ms 11364 KB Output is correct
14 Correct 91 ms 15072 KB Output is correct
15 Correct 98 ms 16228 KB Output is correct
16 Correct 103 ms 18020 KB Output is correct
17 Correct 98 ms 19560 KB Output is correct
18 Correct 103 ms 18008 KB Output is correct
19 Correct 98 ms 20708 KB Output is correct
20 Correct 74 ms 11492 KB Output is correct
21 Correct 57 ms 11748 KB Output is correct
22 Correct 121 ms 20708 KB Output is correct
23 Correct 118 ms 19172 KB Output is correct
24 Correct 121 ms 19172 KB Output is correct
25 Correct 126 ms 23780 KB Output is correct
26 Correct 125 ms 20324 KB Output is correct
27 Correct 116 ms 19300 KB Output is correct
28 Correct 45 ms 4836 KB Output is correct
29 Correct 77 ms 12768 KB Output is correct
30 Correct 75 ms 12648 KB Output is correct
31 Correct 99 ms 12620 KB Output is correct
32 Correct 101 ms 17124 KB Output is correct