Submission #387578

#	Time	Username	Problem	Language	Result	Execution time	Memory
387578		casperwang	Table Tennis (info1cup20_tabletennis)	C++14	100 / 100	627 ms	40876 KiB

tabletennis

#include <bits/stdc++.h>
using namespace std;
#define debug(args...) kout("[ " + string(#args) + " ]", args)
void kout() { cerr << endl; }
template <class T, class ...U> void kout(T a, U ...b) { cerr << a << ' ',kout(b...); }
template <class T> void pary(T L, T R) { while (L != R) cerr << *L << " \n"[++L==R]; }

const int MAXN = 150000;
const int MAXK = 400;
const int B = 1000;
int N, K;
int a[MAXN+MAXK+1];
bool flag[MAXN+MAXK+1];
unordered_map <int,int> arr;

bool check(int S) {
	int nowR = N+K, cnt = 0;
	for (int i = 1; i <= N+K; i++) flag[i] = false;
	for (int i = 1; i < nowR; i++) {
		while (a[i] + a[nowR] > S && nowR > i)
			nowR--;
		if (nowR > i && a[i] + a[nowR] == S) {
			flag[i] = flag[nowR] = true;
			cnt++;
			nowR--;
		}
		if (cnt == N / 2) break;
	}
	return cnt == N / 2;
}

void solve() {
	for (int i = 1; i <= B+1; i++) {
		for (int j = N+K-B; j <= N+K; j++) {
			if (i < j) arr[a[i] + a[j]]++;
		}
	}
	for (auto [v, c] : arr) {
		if (c >= 400 && check(v)) {
			return;
		}
	}
}

void naive() {
	for (int L = 1; L <= K+1; L++) {
		for (int R = N; R <= N+K; R++) {
			if (R-L+1 < N) continue;
			fill(flag+1, flag+1+N+K, false);
			int S = a[L] + a[R], cnt = 1;
			flag[L] = flag[R] = true;
			int nowR = R-1;
			for (int i = L+1; i < nowR; i++) {
				while (a[i] + a[nowR] > S && nowR > i)
					nowR--;
				if (a[i] + a[nowR] == S) {
					flag[i] = flag[nowR] = true;
					cnt++;
					nowR--;
				}
			}
			if (cnt == N / 2) return;
		}
	}
}

signed main() {
	ios_base::sync_with_stdio(0), cin.tie(0);
	cin >> N >> K;
	for (int i = 1; i <= N+K; i++) {
		cin >> a[i];
	}
	if (N+K <= B) {
		naive();
	} else {
		solve();
	}
	for (int i = 1; i <= N+K; i++) {
		if (flag[i]) cout << a[i] << ' ';
	}
	cout << '\n';
	return 0;
}

Compilation message (stderr)

tabletennis.cpp: In function 'void solve()':
tabletennis.cpp:38:12: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   38 |  for (auto [v, c] : arr) {
      |            ^

• Subtask 1: 11 / 11
• Subtask 2: 9 / 9
• Subtask 3: 14 / 14
• Subtask 4: 15 / 15
• Subtask 5: 9 / 9
• Subtask 6: 14 / 14
• Subtask 7: 15 / 15
• Subtask 8: 13 / 13