Submission #113400

#	Time	Username	Problem	Language	Result	Execution time	Memory
113400		TadijaSebez	Flood (IOI07_flood)	C++11	35 / 100	344 ms	34616 KiB

flood

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define mp make_pair
#define pb push_back

struct pt{ ll x,y;pt(){}pt(ll a, ll b):x(a),y(b){}};
bool operator < (pt a, pt b){ return mp(a.x,a.y)<mp(b.x,b.y);}
pt operator - (pt a, pt b){ return pt(a.x-b.x,a.y-b.y);}
ll cross(pt a, pt b){ return a.x*b.y-a.y*b.x;}

const int N=400050;
const int inf=1e9+7;
vector<pair<int,int>> E[N];
pt pts[N];
int u[N],v[N];
int was[N];
vector<int> G[N];
void Find(int x, int y, int e, int bl)
{
	was[e]=bl;
	vector<pair<int,int>> tmp;
    for(auto p:E[y]) tmp.pb(p);
    if(tmp.empty()) return;
    sort(tmp.begin(),tmp.end(),[&](pair<int,int> a, pair<int,int> b)
	{
		if(a.first==x) return false;
		if(b.first==x) return true;
		return cross(pts[a.first]-pts[x],pts[b.first]-pts[x])<0;
	});
    if(was[tmp[0].second]) return;
    Find(y,tmp[0].first,tmp[0].second,bl);
}
void AddEdge(int u, int v){ G[u].pb(v);G[v].pb(u);}
int dist[N];
bool vis[N];
void BFS(int out)
{
	queue<int> q;
	vis[out]=1;
	dist[out]=1;
	q.push(out);
	while(q.size())
	{
		int u=q.front();
		q.pop();
		for(int v:G[u])
		{
			if(!vis[v])
			{
				vis[v]=1;
				dist[v]=dist[u]+1;
				q.push(v);
			}
		}
	}
}
int main()
{
	int n,m,i;
	scanf("%i",&n);
	for(i=1;i<=n;i++) scanf("%lld %lld",&pts[i].x,&pts[i].y);
	scanf("%i",&m);
	for(i=1;i<=m;i++)
	{
		scanf("%i %i",&u[i],&v[i]);
		E[u[i]].pb({v[i],i<<1});
		E[v[i]].pb({u[i],i<<1|1});
	}
	int block=0;
	for(i=2;i<=(m<<1|1);i++) if(!was[i])
	{
		block++;
		if(i&1) Find(v[i>>1],u[i>>1],i,block);
		else Find(u[i>>1],v[i>>1],i,block);
	}
	for(i=1;i<=block;i++) dist[i]=inf,vis[i]=0;
	vector<int> ver;
	vector<int> hor;
	for(i=1;i<=m;i++)
	{
		AddEdge(was[i<<1],was[i<<1|1]);
		if(pts[u[i]].y==pts[v[i]].y) ver.pb(i);
		else hor.pb(i);
	}
	sort(ver.begin(),ver.end(),[&](int x, int y){ return pts[u[x]].x<pts[u[y]].x;});
	for(int id:ver)
	{
		int l;
		if(pts[u[id]].y<pts[v[id]].y) l=id<<1;
		else l=id<<1|1;
		if(!vis[was[l]]) BFS(was[l]);
	}
	sort(hor.begin(),hor.end(),[&](int x, int y){ return pts[u[x]].y<pts[u[y]].y;});
	for(int id:hor)
	{
		int l;
		if(pts[u[id]].x<pts[v[id]].x) l=id<<1|1;
		else l=id<<1;
		if(!vis[was[l]]) BFS(was[l]);
	}
	vector<int> ans;
	for(i=1;i<=m;i++)
	{
		if(dist[was[i<<1]]==dist[was[i<<1|1]]) ans.pb(i);
	}
	printf("%i\n",ans.size());
	for(int a:ans) printf("%i\n",a);
	return 0;
}

Compilation message (stderr)

flood.cpp: In function 'int main()':
flood.cpp:107:26: warning: format '%i' expects argument of type 'int', but argument 2 has type 'std::vector<int>::size_type {aka long unsigned int}' [-Wformat=]
  printf("%i\n",ans.size());
                ~~~~~~~~~~^
flood.cpp:61:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%i",&n);
  ~~~~~^~~~~~~~~
flood.cpp:62:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for(i=1;i<=n;i++) scanf("%lld %lld",&pts[i].x,&pts[i].y);
                    ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
flood.cpp:63:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%i",&m);
  ~~~~~^~~~~~~~~
flood.cpp:66:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%i %i",&u[i],&v[i]);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 0 / 10
• Subtask 3: 10 / 10
• Subtask 4: 0 / 3
• Subtask 5: 0 / 10
• Subtask 6: 0 / 3
• Subtask 7: 3 / 3
• Subtask 8: 3 / 3
• Subtask 9: 0 / 3
• Subtask 10: 0 / 9
• Subtask 11: 9 / 9
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• Subtask 14: 0 / 9