Submission #55529

#	Time	Username	Problem	Language	Result	Execution time	Memory
55529		hamzqq9	Usmjeri (COCI17_usmjeri)	C++14	28 / 140	593 ms	55888 KiB

usmjeri

#include<bits/stdc++.h>
#define lf double
#define ll long long
#define ull unsigned ll
#define ii pair<int,int>
#define li pair<ll,int>
#define iii pair<ii,int>
#define iiii pair<ii,ii>
#define iiii2 pair<int,iii>
#define lii pair<ll,ii>
#define lolo pair<ll,ll>
#define heap priority_queue
#define mp make_pair
#define st first
#define nd second
#define pb push_back
#define pf push_front
#define ppb pop_back
#define ppf pop_front
#define all(x) x.begin(),x.end()
#define len(x) strlen(x)
#define sz(x) (int) x.size()
#define orta ((bas+son)/2)
#define min3(x,y,z) min(min(x,y),z)
#define max3(x,y,z) max(max(x,y),z)
#define umin(x,y) x=min(x,y)
#define umax(x,y) x=max(x,y)
#define dbgs(x) cerr<<(#x)<<" --> "<<(x)<<" "
#define dbg(x) cerr<<(#x)<<" --> "<<(x)<<endl;getchar()
#define MOD 1000000007
#define inf 1000000001
#define N 300005
#define LOG 20
#define magic 100
#define MAX 1000005
#define KOK 350
#define EPS 0.000000000001
#define pw(x) 1ll*((1ll)<<(x))
#define PI 3.1415926535
using namespace std;

int baba[LOG+2][N],der[N],tot[N],way[N];
int x,y,n,m,C;
vector<int> v[N];

int lca(int x,int y) {

	if(der[x]<der[y]) swap(x,y);

	int dx=der[x];

	for(int i=LOG-1;i>=0;i--) {

		if(dx-pw(i)>=der[y]) {

			dx-=pw(i);

			x=baba[i][x];

		}

	}

	if(x==y) return x;

	for(int i=LOG-1;i>=0;i--) {

		if(baba[i][x]!=baba[i][y]) {

			x=baba[i][x];
			y=baba[i][y];

		}

	}

	return baba[0][x];

}

void build_lca() {

	for(int i=1;i<LOG;i++) {

		for(int j=1;j<=n;j++) {

			baba[i][j]=baba[i-1][baba[i-1][j]];

		}

	}

}

void fail() {printf("0");exit(0);}

void make_up(int x,int to,int wyx) {

	while(x!=to && !way[x]) {

		way[x]=wyx;

		x=baba[0][x];

	}

	if(x!=to && way[x]!=wyx) fail();

}

int go_up(int x,int to) {

	while(x!=to) {

		if(way[x]) return way[x];

		C--;

		x=baba[0][x];

	}

	return 0;

}

void dfs(int node,int ata) {

	int ok=0;

	for(int i:v[node]) {

		if(i==ata) continue ;

		dfs(i,node);

		tot[node]+=tot[i];

		ok|=(tot[i]>0);

	}

	if(!tot[node]) C+=(ata>0)+ok;

}

void dfs1(int node,int ata) {

	baba[0][node]=ata;
	der[node]=der[ata]+1;

	for(int i:v[node]) {

		if(i==ata) continue ;		

		dfs1(i,node);

	}

}

int main() {

	#if 0

	freopen("input.txt","r",stdin);

	#endif

	scanf("%d %d",&n,&m);

	C=n-1;

	for(int i=1;i<n;i++) {

		scanf("%d %d",&x,&y);

		v[x].pb(y);
		v[y].pb(x);

	}

	dfs1(1,0);
	build_lca();

	while(m--) {

		scanf("%d %d",&x,&y);

//		tot[x]++;
//		tot[y]++;

		int _lca=lca(x,y);

//		tot[_lca]-=2;

		int way1=go_up(x,_lca);

		if(!way1) {

			way1=3-go_up(y,_lca);

			if(way1==3) {

				C++;

				way1=1;

			}

		}

		make_up(x,_lca,way1);
		make_up(y,_lca,3-way1);

	}

//	dfs(1,0);

	int ans=1;

	for(int i=1;i<=C;i++) ans=ans*2%MOD;

	printf("%d\n",ans);

}

Compilation message (stderr)

usmjeri.cpp: In function 'int main()':
usmjeri.cpp:170:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d",&n,&m);
  ~~~~~^~~~~~~~~~~~~~~
usmjeri.cpp:176:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d",&x,&y);
   ~~~~~^~~~~~~~~~~~~~~
usmjeri.cpp:188:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d",&x,&y);
   ~~~~~^~~~~~~~~~~~~~~

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