Submission #54360

#	Time	Username	Problem	Language	Result	Execution time	Memory
54360		khsoo01	Flood (IOI07_flood)	C++11	100 / 100	141 ms	7564 KiB

flood

#include<bits/stdc++.h>
#define X first
#define Y second
using namespace std;
typedef pair<int,int> pii;

const int N = 200005;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, -1, 0, 1};

int n, m, x[N], y[N], a[N], b[N], nxt[N][4];
bool col[N], vis[N][2];

vector<int> wait, ans;
priority_queue<pair<pii,int> > pq;

int main()
{
	scanf("%d",&n);
	for(int i=1;i<=n;i++) {
		scanf("%d%d",&x[i],&y[i]);
	}
	scanf("%d",&m);
	for(int i=1;i<=m;i++) {
		int A, B;
		scanf("%d%d",&A,&B);
		if(x[A] > x[B] || y[A] > y[B]) swap(A, B);
		a[i] = A;
		b[i] = B;
		if(y[A] == y[B]) {
			nxt[A][0] = i;
			nxt[B][2] = i;
		}
		else {
			nxt[A][3] = i;
			nxt[B][1] = i;
		}
		pq.push({{x[B], -y[B]}, i});
	}
	while(!pq.empty()) {
		int T = pq.top().Y;
		pq.pop();
		if(col[T]) continue;
		int V = a[T], P = (x[a[T]] == x[b[T]] ? 1 : 2);
		for(;;) {
			int D, Z;
			for(int i=0;i<4;i++) {
				D = (P + 3 + i) % 4;
				Z = nxt[V][D];
				if(Z && !col[Z]) break;
			}
			if(vis[Z][D<2]) break;
			vis[Z][D<2] = true;
			wait.push_back(Z);
			V = a[Z] + b[Z] - V;
			P = D;
		}
		for(auto &T : wait) {
			col[T] = true;
		}
		wait.clear();
	}
	for(int i=1;i<=m;i++) {
		if(vis[i][0] && vis[i][1]) ans.push_back(i);
	}
	printf("%d\n",(int)ans.size());
	sort(ans.begin(), ans.end());
	for(auto &T : ans) {
		printf("%d\n",T);
	}
}

Compilation message (stderr)

flood.cpp: In function 'int main()':
flood.cpp:19:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ~~~~~^~~~~~~~~
flood.cpp:21:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d",&x[i],&y[i]);
   ~~~~~^~~~~~~~~~~~~~~~~~~~
flood.cpp:23:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&m);
  ~~~~~^~~~~~~~~
flood.cpp:26:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d",&A,&B);
   ~~~~~^~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 3 / 3
• Subtask 5: 10 / 10
• Subtask 6: 3 / 3
• Subtask 7: 3 / 3
• Subtask 8: 3 / 3
• Subtask 9: 3 / 3
• Subtask 10: 9 / 9
• Subtask 11: 9 / 9
• Subtask 12: 9 / 9
• Subtask 13: 9 / 9
• Subtask 14: 9 / 9