Submission #1125642

#	Time	Username	Problem	Language	Result	Execution time	Memory
1125642		TVSown	Rigged Roads (NOI19_riggedroads)	C++20	100 / 100	489 ms	82632 KiB

riggedroads

///*** Sown_Vipro ***///
/// ->NHI QUOC GIA<- ///

#include<bits/stdc++.h>
using namespace std;
//#pragma GCC optimize ("O3")
//#pragma GCC optimize ("unroll-loops")
//#pragma GCC target("popcnt")
#define F first
#define S second
#define pb push_back
#define pi pair<int, int>
#define pii pair<int, pair<int, int> >
#define FOR(i, a, b) for(int i = a; i <= b; ++i)
#define REP(i, a, b) for(int i = a; i >= b; --i)
#define all(s) s.begin(), s.end()
#define szz(s) int(s.size())
const string NAME = "sown";
const int N = 1e6 + 5, MAX = 1e6, oo = 1e9 + 5, MOD = 1e9 + 7;
void maxi(int &x, int y){ if(x < y) x = y; }
void mini(int &x, int y){ if(x > y) x = y; };
void add(int &x, int y){ x += y; x += MOD * (x < 0); x -= MOD * (x >= MOD); };
int n, m, cur, root;
int p[20][N], idx[N], del[N], h[N], check[N], ans[N], nxt[N];
pi e[N];
vector<pi> adj[N];

void pre(int u){
    h[u] = h[p[0][u]] + 1;
    for(auto [v, i] : adj[u]){
        if(v != p[0][u]){
            p[0][v] = u;
            nxt[v] = u;
            idx[v] = i;
            pre(v);
        }
    }
}

int lca(int u, int v){
    if(h[u] < h[v]) swap(u, v);
    REP(k, 18, 0){
        int pu = p[k][u];
        if(h[pu] >= h[v]) u = pu;
    }
    if(u == v) return u;
    REP(k, 18, 0){
        int pu = p[k][u], pv = p[k][v];
        if(pu != pv){
            u = pu;
            v = pv;
        }
    }
    return p[0][u];
}

int Find(int u){
    if(!del[u]) return u;
    return nxt[u] = Find(nxt[u]);
}

void solve(){
    cin >> n >> m;
    FOR(i, 1, m){
        int u, v; cin >> u >> v;
        e[i] = {u, v};
    }

    FOR(i, 1, n - 1){
        int t; cin >> t;
        check[t] = 1;
        root = e[t].F;
        adj[e[t].F].pb({e[t].S, t});
        adj[e[t].S].pb({e[t].F, t});
    }

    pre(root);
    FOR(k, 1, 18){
        FOR(u, 1, n) p[k][u] = p[k - 1][p[k - 1][u]];
    }
//    FOR(u, 1, n) cout << u << " " << nxt[u] << " " << idx[u] << "\n";

    FOR(i, 1, m){
        int u = e[i].F, v = e[i].S;
        if(ans[i]) continue;
        if(check[i]){
            if(idx[u] == i) del[u] = 1;
            if(idx[v] == i) del[v] = 1;
            ans[i] = ++cur;
            continue;
        }
        int w = lca(u, v);
//        cout << w << "\n";
        vector<int> t;
        while(1){
            u = Find(u);
            if(h[u] <= h[w]) break;
//            cout << u << " " << idx[u] << "\n";
            t.pb(idx[u]);
            del[u] = 1;
        }

        while(1){
            v = Find(v);
            if(h[v] <= h[w]) break;
//            cout << v << " " << idx[v] << "\n";
            t.pb(idx[v]);
            del[v] = 1;
        }

        sort(all(t));

        for(int id : t){
            ans[id] = ++cur;
        }
        ans[i] = ++cur;
//        break;
    }
    FOR(i, 1, m) cout << ans[i] << " ";
}

signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    if(fopen((NAME + ".inp").c_str(), "r")){
        freopen((NAME + ".inp").c_str(), "r", stdin);
//        freopen((NAME + ".out").c_str(), "w", stdout);
    }
    int t = 1;
//    cin >> t;
    while(t--){
        solve();
    }
}

Compilation message (stderr)

riggedroads.cpp: In function 'int main()':
riggedroads.cpp:126:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  126 |         freopen((NAME + ".inp").c_str(), "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 8 / 8
• Subtask 2: 19 / 19
• Subtask 3: 9 / 9
• Subtask 4: 10 / 10
• Subtask 5: 10 / 10
• Subtask 6: 12 / 12
• Subtask 7: 32 / 32