Submission #8533657


Source Code Expand

#include<bits/stdc++.h>
using namespace std;

#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define trav(a, x) for(auto& a : x)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;

bool dfs(int a, int L, vector<vi>& g, vi& btoa, vi& A, vi& B) {
	if (A[a] != L) return 0;
	A[a] = -1;
	trav(b, g[a]) if (B[b] == L + 1) {
		B[b] = 0;
		if (btoa[b] == -1 || dfs(btoa[b], L + 1, g, btoa, A, B))
			return btoa[b] = a, 1;
	}
	return 0;
}

int hopcroftKarp(vector<vi>& g, vi& btoa) {
	int res = 0;
	vi A(g.size()), B(btoa.size()), cur, next;
	for (;;) {
		fill(all(A), 0);
		fill(all(B), 0);
		/// Find the starting nodes for BFS (i.e. layer 0).
		cur.clear();
		trav(a, btoa) if(a != -1) A[a] = -1;
		rep(a,0,sz(g)) if(A[a] == 0) cur.push_back(a);
		/// Find all layers using bfs.
		for (int lay = 1;; lay++) {
			bool islast = 0;
			next.clear();
			trav(a, cur) trav(b, g[a]) {
				if (btoa[b] == -1) {
					B[b] = lay;
					islast = 1;
				}
				else if (btoa[b] != a && !B[b]) {
					B[b] = lay;
					next.push_back(btoa[b]);
				}
			}
			if (islast) break;
			if (next.empty()) return res;
			trav(a, next) A[a] = lay;
			cur.swap(next);
		}
		/// Use DFS to scan for augmenting paths.
		rep(a,0,sz(g))
			res += dfs(a, 0, g, btoa, A, B);
	}
}

const int V = 1.1e7;
bool isPrime[V + 1];

int main() {
	ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	for (int i = 2; i <= V; i++) isPrime[i] = true;
	for (int p = 2; p <= V; p++) {
		if (!isPrime[p]) continue;
		for (int j = p+p; j <= V; j += p) isPrime[j] = false;
	}

	int N; cin >> N;
	vector<int> X(N);
	map<int, int> evtCnt;
	for (int i = 0; i < N; i++) {
		cin >> X[i];
		evtCnt[X[i]] ^= 1;
		evtCnt[X[i]+1] ^= 1;
	}
	vector<int> left;
	vector<int> right;
	for (auto it : evtCnt) {
		if (it.second == 0) continue;
		if (it.first & 1) right.push_back(it.first);
		else left.push_back(it.first);
	}

	int A = int(left.size());
	int B = int(right.size());
	vector<vector<int>> g(A);
	vector<int> btoa(B, -1);
	isPrime[2] = false;
	for (int i = 0; i < A; i++) {
		for (int j = 0; j < B; j++) {
			if (isPrime[abs(left[i] - right[j])]) {
				g[i].push_back(j);
			}
		}
	}

	int ans = hopcroftKarp(g, btoa); // number that can be paired
	cerr << ans << ' ' << A << ' ' << B << '\n';
	A -= ans, B -= ans;
	cout << ans + (A/2) * 2 + (B/2) * 2 + (A % 2 ? 3 : 0) << '\n';

	return 0;
}

Submission Info

Submission Time
Task F - Prime Flip
User ecnerwala
Language C++14 (GCC 5.4.1)
Score 1200
Code Size 2532 Byte
Status AC
Exec Time 86 ms
Memory 11008 KB

Judge Result

Set Name Sample All
Score / Max Score 0 / 0 1200 / 1200
Status
AC × 3
AC × 75
Set Name Test Cases
Sample 0_00.txt, 0_01.txt, 0_02.txt
All 0_00.txt, 0_01.txt, 0_02.txt, 1_00.txt, 1_01.txt, 1_02.txt, 1_03.txt, 1_04.txt, 1_05.txt, 1_06.txt, 1_07.txt, 1_08.txt, 1_09.txt, 1_10.txt, 1_11.txt, 1_12.txt, 1_13.txt, 1_14.txt, 1_15.txt, 1_16.txt, 1_17.txt, 1_18.txt, 1_19.txt, 1_20.txt, 1_21.txt, 1_22.txt, 1_23.txt, 1_24.txt, 1_25.txt, 1_26.txt, 1_27.txt, 1_28.txt, 1_29.txt, 1_30.txt, 1_31.txt, 1_32.txt, 1_33.txt, 1_34.txt, 1_35.txt, 1_36.txt, 1_37.txt, 1_38.txt, 1_39.txt, 1_40.txt, 1_41.txt, 1_42.txt, 1_43.txt, 1_44.txt, 1_45.txt, 1_46.txt, 1_47.txt, 1_48.txt, 1_49.txt, 1_50.txt, 1_51.txt, 1_52.txt, 1_53.txt, 1_54.txt, 1_55.txt, 1_56.txt, 1_57.txt, 1_58.txt, 1_59.txt, 1_60.txt, 1_61.txt, 1_62.txt, 1_63.txt, 1_64.txt, 1_65.txt, 1_66.txt, 1_67.txt, 1_68.txt, 1_69.txt, 1_70.txt, 1_71.txt
Case Name Status Exec Time Memory
0_00.txt AC 81 ms 11008 KB
0_01.txt AC 81 ms 11008 KB
0_02.txt AC 81 ms 11008 KB
1_00.txt AC 81 ms 11008 KB
1_01.txt AC 81 ms 11008 KB
1_02.txt AC 81 ms 11008 KB
1_03.txt AC 81 ms 11008 KB
1_04.txt AC 81 ms 11008 KB
1_05.txt AC 81 ms 11008 KB
1_06.txt AC 80 ms 11008 KB
1_07.txt AC 81 ms 11008 KB
1_08.txt AC 81 ms 11008 KB
1_09.txt AC 81 ms 11008 KB
1_10.txt AC 81 ms 11008 KB
1_11.txt AC 81 ms 11008 KB
1_12.txt AC 81 ms 11008 KB
1_13.txt AC 81 ms 11008 KB
1_14.txt AC 81 ms 11008 KB
1_15.txt AC 81 ms 11008 KB
1_16.txt AC 81 ms 11008 KB
1_17.txt AC 81 ms 11008 KB
1_18.txt AC 81 ms 11008 KB
1_19.txt AC 81 ms 11008 KB
1_20.txt AC 81 ms 11008 KB
1_21.txt AC 81 ms 11008 KB
1_22.txt AC 81 ms 11008 KB
1_23.txt AC 81 ms 11008 KB
1_24.txt AC 82 ms 11008 KB
1_25.txt AC 86 ms 11008 KB
1_26.txt AC 81 ms 11008 KB
1_27.txt AC 81 ms 11008 KB
1_28.txt AC 81 ms 11008 KB
1_29.txt AC 81 ms 11008 KB
1_30.txt AC 81 ms 11008 KB
1_31.txt AC 81 ms 11008 KB
1_32.txt AC 83 ms 11008 KB
1_33.txt AC 80 ms 11008 KB
1_34.txt AC 81 ms 11008 KB
1_35.txt AC 82 ms 11008 KB
1_36.txt AC 81 ms 11008 KB
1_37.txt AC 83 ms 11008 KB
1_38.txt AC 81 ms 11008 KB
1_39.txt AC 81 ms 11008 KB
1_40.txt AC 81 ms 11008 KB
1_41.txt AC 81 ms 11008 KB
1_42.txt AC 81 ms 11008 KB
1_43.txt AC 82 ms 11008 KB
1_44.txt AC 81 ms 11008 KB
1_45.txt AC 81 ms 11008 KB
1_46.txt AC 81 ms 11008 KB
1_47.txt AC 81 ms 11008 KB
1_48.txt AC 81 ms 11008 KB
1_49.txt AC 83 ms 11008 KB
1_50.txt AC 81 ms 11008 KB
1_51.txt AC 81 ms 11008 KB
1_52.txt AC 81 ms 11008 KB
1_53.txt AC 81 ms 11008 KB
1_54.txt AC 81 ms 11008 KB
1_55.txt AC 81 ms 11008 KB
1_56.txt AC 81 ms 11008 KB
1_57.txt AC 84 ms 11008 KB
1_58.txt AC 80 ms 11008 KB
1_59.txt AC 81 ms 11008 KB
1_60.txt AC 80 ms 11008 KB
1_61.txt AC 81 ms 11008 KB
1_62.txt AC 83 ms 11008 KB
1_63.txt AC 82 ms 11008 KB
1_64.txt AC 80 ms 11008 KB
1_65.txt AC 81 ms 11008 KB
1_66.txt AC 80 ms 11008 KB
1_67.txt AC 80 ms 11008 KB
1_68.txt AC 80 ms 11008 KB
1_69.txt AC 80 ms 11008 KB
1_70.txt AC 81 ms 11008 KB
1_71.txt AC 80 ms 11008 KB