Submission #967855

#	Time	Username	Problem	Language	Result	Execution time	Memory
967855		12345678	Regions (IOI09_regions)	C++17	70 / 100	8100 ms	22540 KiB

regions

#include <bits/stdc++.h>

using namespace std;

const int nx=2e5+5, k=500, kx=25005;

#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")

int n, x, q, p, in[nx], out[nx], t, a, b, sz, res;
vector<int> d[nx], r[kx], vin[kx], vout[kx];

struct fenwick
{
    int d[nx];
    void update(int i, int vl) {while (i<nx) d[i]+=vl, i+=(i&-i);}
    int query(int i)
    {
        int res=0;
        while (i>0) res+=d[i], i-=(i&-i);
        return res;
    }
} f;

void dfs(int u)
{
    in[u]=++t;
    for (auto v:d[u]) dfs(v);
    out[u]=t;
}

int bruteforce(int a, int b)
{
    for (auto x:r[b]) f.update(in[x], 1);
    int res=0;
    for (auto x:r[a]) res+=f.query(out[x])-f.query(in[x]-1);
    for (auto x:r[b]) f.update(in[x], -1);
    return res;
}

int main()
{
    scanf("%d %d %d", &n, &sz, &q);
    scanf("%d", &x);
    r[x].push_back(1);
    for (int i=2; i<=n; i++) scanf("%d %d", &p, &x), d[p].push_back(i), r[x].push_back(i);
    dfs(1);
    for (int i=1; i<=sz; i++)
    {
        if (r[i].size()>=k)
        {
            vin[i].resize(kx);
            vout[i].resize(kx);
            for (int j=1; j<=sz; j++) if (i!=j) vin[i][j]=bruteforce(i, j), vout[i][j]=bruteforce(j, i);
        }
    }
    while (q--)
    {
        scanf("%d %d", &a, &b);
        if (r[a].size()>=k) res=vin[a][b];
        else if (r[b].size()>=k) res=vout[b][a];
        else res=bruteforce(a, b);
        printf("%d\n", res);
        fflush(stdout);
    }
}

/*
6 3 4
1
1 2
1 3
2 3
2 3
5 1
*/

Compilation message (stderr)

regions.cpp: In function 'int main()':
regions.cpp:43:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   43 |     scanf("%d %d %d", &n, &sz, &q);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
regions.cpp:44:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   44 |     scanf("%d", &x);
      |     ~~~~~^~~~~~~~~~
regions.cpp:46:35: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   46 |     for (int i=2; i<=n; i++) scanf("%d %d", &p, &x), d[p].push_back(i), r[x].push_back(i);
      |                              ~~~~~^~~~~~~~~~~~~~~~~
regions.cpp:59:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   59 |         scanf("%d %d", &a, &b);
      |         ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 15 / 15
• Subtask 2: 55 / 85