Submission #1212358

#	Time	Username	Problem	Language	Result	Execution time	Memory
1212358		goulthen	Regions (IOI09_regions)	C++20	51 / 100	8090 ms	196608 KiB

regions

//#pragma GCC optimize("O3")
//#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template <class T>
using Tree =
    tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

#define int long long
#define ll long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define fi first
#define se second
#define rep(i, a, b) for (int i = a; i <= b; ++i)
#define per(i, b, a) for (int i = b; i >= a; --i)
#define pb push_back
#define eb emplace_back
#define all(v) (v).begin(), (v).end()
#define lsb(x) (x)&(-x)
 
void setIO(string name = "") {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);cout.tie(nullptr);
    if (!name.empty()) {
        freopen((name + ".in").c_str(), "r", stdin);
        freopen((name + ".out").c_str(), "w", stdout);
    }
}
ll fexp(ll a, ll b, ll m) {
    if (b == 0) return 1LL;
    ll p = a;
    ll ans = 1;
 
    while (b > 0) {
        if (b % 2 != 0) ans = (ans*p)%m;
        p = (p*p)%m;
        b >>= 1;
    }
    return ans;
}
 
const int MAXN = 4e5 + 10;
const int INF = 1e18+5;
const int MOD = 1e9+7;
vector<int> g[MAXN], id[25010];
int ti[MAXN], to[MAXN], R[MAXN], dp[500][500], pfx[MAXN][500],bit[MAXN],q,n, t= 0;
//WOW I guess subtask really are helpful
// subtask #1 and #2 can't happen at the same time!

void update(int i, int x) {
    for (;i <= 2*n; i += lsb(i)) bit[i] += x;
}

int query(int i) {
    int qq = 0;
    for (; i > 0; i -= lsb(i)) qq += bit[i];
    return qq;
}

void dfs(int u, int p = -1) {
    ti[u] = t++;
    for (const int &v : g[u]) {
        if (v==p) continue;
        dfs(v,u);
    }
    to[u] = t++;
}

void smallR() {
    //TODO: precalc;
    rep(i,1,n) {
        pfx[to[i]][R[i]] = 1;
    }
    rep(i,1,2*n) {
        rep(j,1,500) {
            pfx[i][j] += pfx[i-1][j];
        }
    }

    rep(i,1,n) {
        rep(j,1,500) {
            dp[R[i]][j] += pfx[to[i]][j] - pfx[ti[i]][j];
        }
    }

    while (q--) {
        int a,b;cin >> a >> b;
        cout << dp[a][b] << endl;
    }
}

void bigR() {
    while (q--) {
        int a,b;cin >> a >> b;
        for (auto &i: id[b]) update(to[i],1);
        int ans = 0;
        for (auto &i: id[a]) ans += query(to[i]) - query(ti[i]);

        cout << ans << endl;
        for (auto &i: id[b]) update(to[i],-1);
    }
}


void solve() {
    int r;cin >> n >> r >> q;
    cin >> R[1];
    id[R[1]].pb(1);
    rep(i,2,n) {
        int pr,rg;cin >> pr >> rg;
        R[i] = rg;
        id[rg].pb(i);
        g[i].pb(pr);
        g[pr].pb(i);
    }
    dfs(1);

    if (r<=500) smallR();
    else bigR();
}


int32_t main() {
    //setIO();
    int tt = 1;
    //cin >> tt;

    while (tt-- > 0) solve();
    
}

Compilation message (stderr)

regions.cpp: In function 'void setIO(std::string)':
regions.cpp:28:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   28 |         freopen((name + ".in").c_str(), "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
regions.cpp:29:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   29 |         freopen((name + ".out").c_str(), "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
regions.cpp: In function 'void smallR()':
regions.cpp:85:25: warning: iteration 499 invokes undefined behavior [-Waggressive-loop-optimizations]
   85 |             dp[R[i]][j] += pfx[to[i]][j] - pfx[ti[i]][j];
      |             ~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
regions.cpp:17:40: note: within this loop
   17 | #define rep(i, a, b) for (int i = a; i <= b; ++i)
      |                                        ^
regions.cpp:84:9: note: in expansion of macro 'rep'
   84 |         rep(j,1,500) {
      |         ^~~
regions.cpp:79:23: warning: iteration 499 invokes undefined behavior [-Waggressive-loop-optimizations]
   79 |             pfx[i][j] += pfx[i-1][j];
      |             ~~~~~~~~~~^~~~~~~~~~~~~~
regions.cpp:17:40: note: within this loop
   17 | #define rep(i, a, b) for (int i = a; i <= b; ++i)
      |                                        ^
regions.cpp:78:9: note: in expansion of macro 'rep'
   78 |         rep(j,1,500) {
      |         ^~~

• Subtask 1: 11 / 15
• Subtask 2: 40 / 85