Submission #1228815

#	Time	Username	Problem	Language	Result	Execution time	Memory
1228815		trinm01	Regions (IOI09_regions)	C++20	100 / 100	2650 ms	47996 KiB

regions

#include <bits/stdc++.h>
using namespace std;

#define int long long 
#define ll long long
#define FOR(i, l, r) for (int i = (l); i <= (r); i++)
#define FOD(i, r, l) for (int i = (r); i >= (l); i--)
#define fi first
#define se second
#define pii pair<int, int>

const ll mod = 1e9 + 7;
const int MAXN = 200000 + 5;
const ll oo = 1e18;  
const int base = 500;

int n, r, q;
int a[MAXN];
vector<int> adj[MAXN];

int c[MAXN];
void dfs(int u, int w, int sum){
    for(auto v:adj[u]){
        c[a[v]]+=sum;
        dfs(v, w, sum+(a[v]==w));
    }
}

vector<pii> vec[MAXN];
int in[MAXN], out[MAXN], cnt;
void dfs1(int u){
    in[u]=++cnt;
    for(auto v:adj[u]){
        dfs1(v);
    }
    out[u]=cnt;
    vec[a[u]].push_back({in[u], out[u]});
}

vector<int> nang[MAXN];

signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    if(fopen(".inp", "r")){
        freopen(".inp", "r", stdin);
        freopen(".out", "w", stdout);
    }

    cin >> n >> r >> q;
    cin >> a[1];
    FOR(i, 2, n){
        int par, w;
        cin >> par >> w;
        a[i]=w;
        adj[par].push_back(i);
    }
    FOR(i, 1, r){
        vec[i].push_back({-oo, 0});
    }
    dfs1(1);
    FOR(i, 1, r){
        vec[i].push_back({oo, 0});
    }
    FOR(i, 1, r){
        sort(vec[i].begin(), vec[i].end());
    }
    FOR(i, 1, q){
        int r1, r2;
        cin >> r1 >> r2;
        // if(i==1){
        //     for(auto [l, r]:vec[r1]){
        //         cout << l << ' ' << r << '\n';
        //     }
        // }
        if(vec[r1].size()<base){
            int ans=0;
            for(auto [l, r]:vec[r1]){
                if(l==-oo || l==oo) continue;
                ans-=lower_bound(vec[r2].begin(), vec[r2].end(), make_pair(l, 0LL))-vec[r2].begin()-1;
                ans+=upper_bound(vec[r2].begin(), vec[r2].end(), make_pair(r, oo))-vec[r2].begin()-1;
            }
            cout << ans;
        }
        else{
            if(nang[r1].empty()){
                FOR(j, 1, r){
                    c[j]=0;
                }
                dfs(1, r1, a[1]==r1);
                nang[r1].push_back(0);
                FOR(j, 1, r){
                    nang[r1].push_back(c[j]);
                }
            }
            cout << nang[r1][r2];
        }
        cout << '\n';
        cout << flush;
    }
    

    return 0;
}

Compilation message (stderr)

regions.cpp: In function 'int main()':
regions.cpp:48:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   48 |         freopen(".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~
regions.cpp:49:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   49 |         freopen(".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~

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