Submission #256106

#	Time	Username	Problem	Language	Result	Execution time	Memory
256106		tomsyd	T-Covering (eJOI19_covering)	C++17	0 / 100	1 ms	384 KiB

covering

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

vector<pair<int,int>> pos;
vector<pair<int,int>> dir = {{1,0},{0,-1},{-1,0},{0,1}};
vector<vector<bool>> notin;
vector<vector<int>> grid;
int n,m;

int solve(int idx, int crt_ans){
	if (idx == pos.size()) return crt_ans;
	int ans = -1, A = pos[idx].first, B = pos[idx].second;
	if (notin[A][B]) return 0;
	notin[A][B] = true;
	for (int j=0; j<4; ++j){
		int a = crt_ans+grid[A][B];
		for (int k=0; k<3; ++k){
			int AA = A+dir[(j+k)%4].first, BB = B+dir[(j+k)%4].second;
			if (AA >= n or BB >= m or AA < 0 or BB < 0 or notin[AA][BB]){
				a = -1;
				break;
			}
			a += grid[AA][BB];
		}
		if (a == -1) continue;
		for (int i=0; i<3; ++i){
			notin[A+dir[(j+i)%4].first][B+dir[(j+i)%4].second] = true;
		}
		ans = max(ans,solve(idx+1,a));
		for (int i=0; i<3; ++i){
			notin[A+dir[(j+i)%4].first][B+dir[(j+i)%4].second] = false;
		}
	}
	notin[A][B] = false;
	return ans;
}

bool check(){
	for (int i=0; i<pos.size(); ++i){
		for (int j=i+1; j<pos.size(); ++j){
			if (abs(pos[i].first-pos[j].first) <= 1 or abs(pos[i].second-pos[j].second) <= 1) return false;
		}
	}
	return true;
}

int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cin >> n >> m;
	grid = vector<vector<int>>(n,vector<int>(m));
	notin = vector<vector<bool>>(n,vector<bool>(m));
	for (int i=0; i<n; ++i){
		for (int j=0; j<m; ++j){
			cin >> grid[i][j];
		}
	}
	int q;
	cin >> q;
	for (int i=0; i<q; ++i){
		int x,y;
		cin >> x >> y;
		pos.emplace_back(x,y);
	}
	if (pos.size() > 2){
		cout << "No";
		return 0;
	}
//	if (check()){
/*	{
		int ans = 0;
		for (int i=0; i<q; ++i){
			int best = -1;
			for (int j=0; j<4; ++j){
				int A = grid[pos[i].first][pos[i].second];
				for (int a=0; a<3; ++a){
					int AA = pos[i].first+dir[(a+j)%4].first, BB = pos[i].second+dir[(a+j)%4].second;
					if (AA < 0 or BB < 0 or AA >= n or BB >= m){
						A = -1;
						break;
					}
					A += grid[AA][BB];
				}
				best = max(best,A);
			}
			if (best == -1){
				ans = -1;
				break;
			}
			ans += best;
		}
		if (ans == -1) cout << "No";
		else cout << ans;
		return 0;
//	}
	}
*/	int ans = solve(0,0);
	if (ans == -1) cout << "No" << '\n';
	else cout << ans << '\n';
	return 0;
}

Compilation message (stderr)

covering.cpp: In function 'int solve(int, int)':
covering.cpp:11:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  if (idx == pos.size()) return crt_ans;
      ~~~~^~~~~~~~~~~~~
covering.cpp: In function 'bool check()':
covering.cpp:39:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i=0; i<pos.size(); ++i){
                ~^~~~~~~~~~~
covering.cpp:40:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j=i+1; j<pos.size(); ++j){
                   ~^~~~~~~~~~~

• Subtask 1: 0 / 5
• Subtask 2: 0 / 10
• Subtask 3: 0 / 10
• Subtask 4: 0 / 10
• Subtask 5: 0 / 15
• Subtask 6: 0 / 20
• Subtask 7: 0 / 30