Submission #1255016

#	Time	Username	Problem	Language	Result	Execution time	Memory
1255016		ByeWorld	Triple Peaks (IOI25_triples)	C++20	78.56 / 100	211 ms	33208 KiB

triples

#include "triples.h"
#include <bits/stdc++.h>
#define ll long long
#define pb push_back
using namespace std;
typedef pair<int,int> pii;
const int MAXN = 5e5+10;
const int SQRT = 500;
void chmx(auto &a, auto b){ a = max(a,b); }
void chmn(auto &a, auto b){ a = min(a,b); }

int n, h[MAXN];
ll ans;
void cek(int i, int j, int k){
	if(1<=i && i<j && j<k && k<=n){
		// if(ty==1 && h[i] <= max(h[j], h[k])) return;

		int mxa = -1, mxb = -1, mna = MAXN, mnb = MAXN, tota=0, totb=0;
		chmx(mxa, h[i]); chmn(mna, h[i]); tota += h[i];
		chmx(mxa, h[j]); chmn(mna, h[j]); tota += h[j];
		chmx(mxa, h[k]); chmn(mna, h[k]); tota += h[k];

		chmx(mxb, j-i); chmn(mnb, j-i); totb += j-i;
		chmx(mxb, k-j); chmn(mnb, k-j); totb += k-j;
		chmx(mxb, k-i); chmn(mnb, k-i); totb += k-i;

		if(mxa==mxb && mna==mnb && tota==totb) ans++; 
	}
}

vector<int> vec[MAXN], tag[MAXN];
long long count_triples(std::vector<int> H) {
	n = H.size(); ans = 0;
	for(int i=0; i<=2*n; i++){
		vec[i].clear(); tag[i].clear();
	}
	for(int i=1; i<=n; i++) h[i] = H[i-1];

	for(int i=1; i<=n; i++){ // i max
		int k = h[i]+i;
		cek(i, i+h[k], k);
		if(i+h[k] != k-h[k]) cek(i, k-h[k], k);
	}
	for(int k=1; k<=n; k++){ // k max
		int i = k-h[k];
		cek(i, i+h[i], k);
		if(i+h[i] != k-h[i]) cek(i, k-h[i], k);
	}

	for(int i=1; i<=n; i++){ // j max
		int j = i+h[i];
		if(h[i] != i+h[j]-j) cek(i, j, i+h[j]);
	}
	for(int i=1; i<=n; i++)
		vec[h[i]-i + n].pb(i);

	for(int idx=0; idx<=2*n; idx++){ // j max
		if(vec[idx].size() < SQRT){
			for(int a=0; a<vec[idx].size(); a++){
				for(int b=a+1; b<vec[idx].size(); b++){
					int i = vec[idx][a], j = vec[idx][b];
					cek(i, j, h[j]+i);
				}
			}
		} else {
			for(auto i : vec[idx])
				tag[h[i]+i].pb(i);
			for(int k=1; k<=n; k++){
				for(auto j : tag[h[k]+k]){
					cek(k-h[j], j, k);
				}
			}
			for(auto i : vec[idx])
				tag[h[i]+i].clear();
		}
	}
	return ans;
}

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

std::vector<int> construct_range(int M, int K) {
	vector<int> ans;
	while(ans.size() < M){
		vector<int> te =
			{1, 3, 2, 3, 4, 1, 2, 1, 3, 1, 2, 1, 4, 3, 2, 3, 1, 2, 1, 4};
		for(auto in : te) ans.pb(in);
	}
	return ans;
	/*
	for(int i=0; i<M; i++){
		for(int j=i+1; j<M; j++){
			for(int p=1; p<=4; p++){
				for(int q=1; q<=4; q++){
					vector <int> cob = te;
					cob[i] = p; cob[j] = q;
					if(count_triples(cob) == K){

			cout << " ket\n";
			for(auto in : cob) cout << in << ' ';
			cout << '\n';
					}
				}
			}
		}
	}
	cout << "nein\n";
	ll mx = -1; vector<int> ans;
	while(mx < K){
		vector<int> te;
		for(int i=0; i<M; i++) te.pb(rng()%4+1);

		ll has = count_triples(te);

		for(int i=0; i<M; i++){
			int aw = te[i];
			te[i] = rng()%4+1;
			ll baru = count_triples(te);
			if(baru < has)
				te[i] = aw;
		}
		for(int i=0; i<M; i++){
			int aw = te[i];
			te[i] = rng()%4+1;
			ll baru = count_triples(te);
			if(baru < has)
				te[i] = aw;
		}

		has = count_triples(te);
		if(has > mx){
			mx = has;
			ans = te;

			cout << has << " ket\n";
			for(auto in : ans) cout << in << ' ';
			cout << '\n';
		}
	}
	return ans;
	*/
}

• Subtask 0: 0 / 0
• Subtask 1: 8 / 8
• Subtask 2: 6 / 6
• Subtask 3: 10 / 10
• Subtask 4: 11 / 11
• Subtask 5: 16 / 16
• Subtask 6: 19 / 19
• Subtask 7: 5 / 5
• Subtask 8: 1.935 / 5
• Subtask 9: 0.7749 / 5
• Subtask 10: 0.3321 / 5
• Subtask 11: 0.3875 / 5
• Subtask 12: 0.1292 / 5