Submission #126617

#	Time	Username	Problem	Language	Result	Execution time	Memory
126617		khulegub	Flood (IOI07_flood)	C++14	0 / 100	2 ms	376 KiB

flood

#include <bits/stdc++.h>
#define mp make_pair
#define pb push_back
#define xx first
#define yy second
using namespace std;
typedef pair<int, int> pii;

vector<vector<int> > to;
vector<pii> p;
int n;
int w;
int uld;
bool path[100010];
bool vis[100010];

int cmpx (int a, int b){
	return p[b].xx - p[a].xx;
}
int cmpy (int a, int b){
	return p[b].yy - p[a].yy;
}
void mark (int u){
	vis[u] = 1;
	for (int i = 0; i < 4; i++){
		if(to[u][i] != 0 && !vis[to[u][i]] ){
			mark (to[u][i]);
		}
	}
}
int dfs (int u, int pre, int dir){
	if (path[u]) return -1; // ustga >:(
	if(dir == -1){
		for (int i = 0; i < 4; i++){
			if(to[u][i] != 0){
				int tmp = dfs(to[u][i], u, i);
				if(tmp == -1){
					uld--;
					to[u][i] = 0;
					to[ to[u][i] ][ (i + 2) % 4 ] = 0;
					return -1;
				}
			}
		}
	}
	int arr[4];
	arr[0] = (dir + 1) % 4;
	arr[1] = dir;
	arr[2] = (dir + 3) % 4;
	path[u] = 1;
	for (int i = 0; i < 3; i++){
		if (to[u][arr[i]] != 0){
			int tmp = dfs(to[u][arr[i]], u, arr[i]);
			if(tmp == -1){
				uld--;
				to[u][arr[i]] = 0;
				to[ to[u][arr[i]] ][ (arr[i] + 2) % 4 ] = 0;
				return -1;
				// HUBCoworking
			}
		}
	}
	path[u] = 0;
	return 1;
}
// bool 
int main() {
	freopen("in.txt", "r", stdin);
	cin >> n;
	to.resize(n + 1, vector<int>(4) );
	p.resize(n + 1);
	vector<pii> wll;
	for (int i = 1, tx, ty; i <= n; i++){
		cin >> tx >> ty;
		p[i] = mp(tx, ty);
	}
	cin >> w;
	uld = w;
	wll.resize(w + 1);
	// cout << to[1].size();
	for (int i = 1, a, b; i <= w; i++){
		cin >> a >> b;
		int dx = p[b].xx - p[a].xx, dy = p[b].yy - p[a].yy;
		if(dy == 0){
			if(dx > 0){ // b ni a giin baruun tald
				to[a][1] = b;
				wll[i] = mp(a,1);
				to[b][3] = a;
			}
			else{
				to[a][3] = b;
				wll[i] = mp(a,3);
				to[b][1] = a;
			}
		}
		else if(dx == 0){
			if(dy > 0){ // b ni a giin deed tald
				to[a][0] = b;
				wll[i] = mp(a,0);
				to[b][2] = a;
			}
			else{
				to[a][2] = b;
				wll[i] = mp(a,2);
				to[b][0] = a;
			}
		}
	}
	// cout << to[1][];
	for (int i = 1; i <= n; i++){
		// cout << to[i][] << ' ';
		if(!vis[i]){
			dfs(i, i, -1);
			mark(i);
		}
	}
	cout << uld << '\n';
	for(int i = 1; i <= w; i++){
		if (to[wll[i].xx][wll[i].yy] != 0 ) cout << i << '\n';
	}
	return 0;
}

Compilation message (stderr)

flood.cpp: In function 'int main()':
flood.cpp:68:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
  freopen("in.txt", "r", stdin);
  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 10
• Subtask 4: 0 / 3
• Subtask 5: 0 / 10
• Subtask 6: 0 / 3
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