Submission #629670

#	Time	Username	Problem	Language	Result	Execution time	Memory
629670		lovrot	T-Covering (eJOI19_covering)	C++11	100 / 100	175 ms	46632 KiB

covering

#include <bits/stdc++.h> 
#include <unistd.h>

#define X first
#define Y second
#define ll long long
#define pii pair<int, int>
#define pb push_back
#define vec vector
#define pri(i, poc, n, pov) for(int i = (int) poc; i < (int) n; i += (int) pov)
#define od(i, poc, n, pov) for(int i = (int) poc; i > (int) n; i -= (int) pov)

using namespace std;

const int INF = 1e9;
const int lx[8] = {1, -1, 0, 0, -1, 1, 1, -1};
const int ly[8] = {0, 0, 1, -1, -1, 1, -1, 1};
const int N = 1e6 + 10;

int n, m, q;
int cdeg[N], vis[N];

vec<vec<int>> mat, spec;
vec<vec<bool>> bio, xp;
vec<pii> vx;
vec<int> g[N];

void fail(){ 
	cout << "No\n";
	exit(0);
}

void success(){ 
	int ans = 0;
	pri(i, 1, n + 1, 1) 
		pri(j, 1, m + 1, 1)
			ans += (bio[i][j] ? mat[i][j] : 0);
	cout << ans << "\n";
}

void markPlus(int x, int y){ 
	bio[x][y] = 1;
	pri(i, 0, 4, 1)
		bio[x + lx[i]][y + ly[i]] = 1;
}

void countBan(int x, int y){ 
	int cnt = bio[x][y];
	pri(i, 0, 4, 1){ 
		cnt += bio[x + lx[i]][y + ly[i]];
	}
	if(cnt > 1) fail(); 
}

void tryPlace(int x, int y){ 
	countBan(x, y);
	markPlus(x, y);
}

pii findLow(int x, int y){ 
	pii ret;
	int mn = INF;
	pri(i, 0, 4, 1)
		if(mat[x + lx[i]][y + ly[i]] < mn){ 
			mn = mat[x + lx[i]][y + ly[i]];
			ret = {x + lx[i], y + ly[i]};
		}
	return ret;
}

//+
vec<vec<int>> createMat(int h, int w){ 
	vec<vec<int>> ret;
	pri(i, 0, h, 1){
		vec<int> line;
		pri(j, 0, w, 1) 
			line.pb(0);
		ret.pb(line);
	}
	return ret;
}

//+
vec<vec<bool>> createBio(int h, int w){ 
	vec<vec<bool>> ret;
	pri(i, 0, h, 1){
		vec<bool> line;
		pri(j, 0, w, 1) 
			line.pb(0);
		ret.pb(line);
	}
	return ret;
}

bool isCyc(int u, int p){
	if(vis[u]) return true; 
	vis[u] = true;
	for(int v : g[u]){ 
		if(v != p && vis[v]){ 
			vis[u] = false;
			return true;
		}
		if(v == p) continue;
		if(isCyc(v, u)) {
			vis[u] = false;
			return true;
		}
	}
	vis[u] = false;
	return false;
}

pii rek2(int u){ 
	pii ret = {1, g[u].size()};
	vis[u] = true;
	markPlus(vx[u].X, vx[u].Y);
	for(int v : g[u]){ 
		//cout << u << " " << v << "\n";
		if(vis[v]) continue;
		pii res = rek2(v);
		ret.X += res.X;
		ret.Y += res.Y;
	}	
	return ret;
}

pii rek(int u){ 
	if(vis[u]) return {0, 0};
	vis[u] = true;
	tryPlace(vx[u].X, vx[u].Y);
	pii p = findLow(vx[u].X, vx[u].Y);
	for(int v : g[u]){ 
		if(vis[v]) continue;
		pii res = rek(v);
		if(mat[p.X][p.Y] > mat[res.X][res.Y])
			swap(p, res);
	}
	return p;
}

void init(){ 
	cin >> n >> m;
	
	bio = createBio(n + 2, m + 2);	
	xp = createBio(n + 2, m + 2);
	mat = createMat(n + 2, m + 2);
	spec = createMat(n + 2, m + 2);

	mat[0][0] = INF;

	pri(i, 1, n + 1, 1)
		pri(j, 1, m + 1, 1) 
			cin >> mat[i][j];
	// pri(i, 0, n + 2, 1) 
	// 	xp[i][0] = xp[i][m + 1] = 1;
	// pri(i, 0, m + 2, 1){ 
	// 	xp[0][i] = xp[n + 1][i] = 1;
	// }

	cin >> q;

	pri(i, 0, q, 1){ 
		int x, y;
		cin >> x >> y;
		x++;
		y++;
		vx.pb({x, y});
		xp[x][y] = true;
		spec[x][y] = i + 1;
	}
}

int main(){ 
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);

	init();

	// cout << "da\n";
	//close edges
	pri(i, 0, q, 1){ 
		int x = vx[i].X;
		int y = vx[i].Y;
		pri(j, 0, 8, 1){ 
			int nx = x + lx[j];
			int ny = y + ly[j];
			if(xp[nx][ny] || (nx == 0 && ny == y) || (nx == n + 1 && ny == y) || (ny == 0 && nx == x) || (ny == m + 1 && nx == x)){ 
				cdeg[i]++;
			}
			if(j < 4){ 
				nx += lx[j];
				ny += ly[j];
				if(nx > 0 && nx < n + 1 && ny > 0 && ny < m + 1 && spec[nx][ny])
					g[i].pb(spec[nx][ny] - 1);
			}
		}
		// cout << i << " " << cdeg[i] << "\n";
		if(cdeg[i] > 1) fail();
		if(cdeg[i] == 1){
			vis[i] = true;	
			markPlus(x, y);
		} 
	}

	//cover groups touching close-pairs
	pri(i, 0, q, 1){ 
		if(cdeg[i] == 1){ 
			for(int v : g[i]){
				if(cdeg[v] == 1) fail();
				rek(v);
			}
		}
	}

	
	pri(i, 0, q, 1){ 
		if(vis[i]) continue;
		bool res = isCyc(i, -1);
		if(!res){ 
			pii p = rek(i);
			bio[p.X][p.Y] = false;
		} else { 
			pii ret = rek2(i);
			if(ret.X - ret.Y / 2 < 0) fail();	
		}
	}
	// pri(i, 1, n + 1, 1)
	// 	pri(j, 1, m + 1, 1)
	// 		cout << bio[i][j] << " \n"[j == m];
	success();
	return 0;
}

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