Submission #899902

#	Time	Username	Problem	Language	Result	Execution time	Memory
899902		boyliguanhan	Regions (IOI09_regions)	C++17	90 / 100	8090 ms	80924 KiB

regions

#include<bits/stdc++.h>
#define l int
int read(){
    char x = getchar();
    int val = 0;
    while(x<'0'||x>'9')x=getchar();
    while('0'<=x&&x<='9')
        val = val*10+x-'0', x=getchar();
    return val;
}
using namespace std;
vector<l> adj[200001];
vector<pair<l,l>> arr[25001];
l region[200001], t, ans1[51][25001], ans2[25001][51], in[200001], out[200001], li[200001], sz[25001], lg[51];
void merge(unordered_map<l, l> &a, unordered_map<l, l> b){
    if(a.size()<b.size())
        swap(a, b);
    for(auto i: b)
        a[i.first]+=i.second;
}
unordered_map<l,l> dfs(l n){
    unordered_map<l,l> cur;
    cur[region[n]]=1;
    in[n]=t++;
    arr[region[n]].push_back({in[n],1});
    for(auto i: adj[n]){
        merge(cur, dfs(i));
    }
    out[n]=t++;
    arr[region[n]].push_back({out[n],-1});
    if(li[region[n]])
        for(auto i: cur)
            ans1[li[region[n]]][i.first]+=i.second;
    else
        for(auto i: lg)
            ans2[region[n]][li[i]]+=cur[i];
    return cur;
}
l query_s(int r1, int r2){
    l sum=0, o=0, a=0, b=0;
    while(a<arr[r1].size()&&b<arr[r2].size()){
        if(arr[r1][a]<arr[r2][b])
            o+=arr[r1][a].second, a++;
        else
            sum+=o, b++;
    }
    return sum/2;
}
int main(){
    l n=read(), r=read(), q=read(), lr=0;
    region[1]=read();
    for(l i = 2; i <= n; i++){
        adj[read()].push_back(i);
        region[i] = read();
        sz[region[i]]++;
    }
    for(int i = 1; i <= r; i++)
        if(sz[i]>4000)
            lg[lr]=i, li[i]=++lr;
    dfs(1);
    while(q--){
        int r1=read(), r2=read();
        if(li[r1])
            cout << ans1[li[r1]][r2] << endl;
        else if(li[r2])
            cout << ans2[r1][li[r2]] << endl;
        else
            cout << query_s(r1, r2) << endl;
    }
    return 0;
}

Compilation message (stderr)

regions.cpp: In function 'int query_s(int, int)':
regions.cpp:41:12: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   41 |     while(a<arr[r1].size()&&b<arr[r2].size()){
      |           ~^~~~~~~~~~~~~~~
regions.cpp:41:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   41 |     while(a<arr[r1].size()&&b<arr[r2].size()){
      |                             ~^~~~~~~~~~~~~~~

• Subtask 1: 15 / 15
• Subtask 2: 75 / 85