Submission #1264427

#	Time	Username	Problem	Language	Result	Execution time	Memory
1264427		Tymond	Triple Peaks (IOI25_triples)	C++20	11 / 100	27 ms	15688 KiB

triples

#include "triples.h"
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
#define fi first
#define se second
#define vi vector<int>
#define vll vector<long long>
#define pii pair<int, int>
#define pll pair<long long, long long>
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
mt19937_64 rng64(chrono::high_resolution_clock::now().time_since_epoch().count());
inline int rand(int l,int r){return uniform_int_distribution<int>(l, r)(rng);}
inline ll rand(ll l,ll r){return uniform_int_distribution<ll>(l, r)(rng64);}
#ifdef DEBUG
auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";}
#define debug(X...)cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X)
#else
#define debug(...){}
#endif

struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }

    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};

struct pair_hash{
  size_t operator()(const pair<int,int>&x)const{
    return hash<long long>()(((long long)x.first)^(((long long)x.second)<<32));
  }
};

const int B = 369;

ll count_triples(vi H){
    ll ans = 0LL;
    int n = sz(H);
    vector<vi> vec(2 * n + 1, vi());
    for(int i = 0; i < n; i++){
        if(i + H[i] < n && H[i + H[i]] > H[i] && i + H[i + H[i]] < n && H[i + H[i + H[i]]] == H[i + H[i]] - H[i]){
            ans++;
        }

        if(i + H[i] < n && H[i + H[i]] < H[i]){
            if(H[i + H[i + H[i]]] == H[i] - H[i + H[i]]){
                ans++;
            }

            if(H[i + H[i] - H[i + H[i]]] == H[i] - H[i + H[i]] && i + H[i] - H[i + H[i]] != i + H[i + H[i]]){
                ans++;
            }
        }

        if(i - H[i] >= 0 && H[i - H[i]] < H[i]){
            if(H[i - H[i - H[i]]] == H[i] - H[i - H[i]]){
                ans++;
            }

            if(H[i - H[i] + H[i - H[i]]] == H[i] - H[i - H[i]] && i - H[i] + H[i - H[i]] != i - H[i - H[i]]){
                ans++;
            }
        }
        vec[H[i] - i + n].pb(i);
    }

    for(int x = 0; x < 2 * n + 1; x++){
        if(sz(vec[x]) > B){
            int X = x - n;
            for(int k = 0; k < n; k++){
                if(H[k] - k == X){
                    continue;
                }
                if((k - H[k] - X) & 1){
                    continue;
                }
                int i = (k - H[k] - X) / 2;
                int j = H[k] + i;
                if(i < j && j < k && H[i] - i == X && H[j] - j == X && H[k] == j - i){
                    ans++;
                }
            }
        }else{
            for(int i = 0; i < sz(vec[x]); i++){
                for(int j = i + 1; j < sz(vec[x]); j++){
                    if(H[vec[x][j]] > H[vec[x][i]] && H[vec[x][j]] - H[vec[x][i]] == H[vec[x][i] + H[vec[x][j]]] && vec[x][i] + H[vec[x][j]] == vec[x][j] + H[vec[x][i]]){
                        ans++;
                    }
                }
            }
        }
    }
    return ans;
}

vi construct_range(int M, int K){
    return {1, 1, 1};
}

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• Subtask 1: 0 / 8
• Subtask 2: 0 / 6
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• Subtask 4: 11 / 11
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• Subtask 12: 0 / 5