Submission #1112214

#	Time	Username	Problem	Language	Result	Execution time	Memory
1112214		mariaclara	One-Way Streets (CEOI17_oneway)	C++17	100 / 100	79 ms	16532 KiB

oneway

#include<bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int,int> pii;
const int MAXN = 1e5 + 5;
#define all(x) x.begin(), x.end();
#define sz(x) (int)x.size()
#define mk make_pair 
#define pb push_back 
#define fr first 
#define sc second 

int n, m, p, up_edge[MAXN], ponte[MAXN], val[MAXN];
int niv[MAXN], vis[MAXN];
int A[MAXN], B[MAXN], S[MAXN], E[MAXN];
vector<pii> edges[MAXN];
string ans;

int dfs(int x, int up_edge) {
    vis[x] = 1;

    int lower_back = n;
    for(auto [viz, ind] : edges[x]) {
        if(!vis[viz]) {
            niv[viz] = niv[x] + 1;

            lower_back = min(lower_back, dfs(viz, ind));
        }
        else if(ind != up_edge) lower_back = min(lower_back, niv[viz]);
    }

    if(lower_back >= niv[x]) ponte[x] = 1;
    return lower_back;
}

int calc_ans(int x, int up_edge) {
    vis[x] = 1;

    int at_val = val[x];
    for(auto [viz, ind] : edges[x]) {
        if(!vis[viz])
            at_val += calc_ans(viz, ind);
    }

    if(at_val > 0 and ponte[x]) {
        if(A[up_edge] == x) ans[up_edge] = 'R';
        else ans[up_edge] = 'L';
    }

    if(at_val < 0 and ponte[x]) {
        if(A[up_edge] == x) ans[up_edge] = 'L';
        else ans[up_edge] = 'R';
    }

    return at_val;
}
int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    cin >> n >> m;

    for(int i = 0; i < m; i++) {
        cin >> A[i] >> B[i];
        edges[A[i]].pb({B[i], i});
        edges[B[i]].pb({A[i], i});
        ans += 'B';
    }

    cin >> p;
    
    for(int i = 1; i <= p; i++)
        cin >> S[i] >> E[i], val[S[i]]++, val[E[i]]--;

    for(int i = 1; i <= n; i++)
        if(!vis[i]) dfs(i, -1), ponte[i] = 0;

    memset(vis, 0, sizeof(vis));
    for(int i = 1; i <= n; i++)
        if(!vis[i]) calc_ans(i, 0);

    cout << ans;
}

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