Submission #1070582

#	Time	Username	Problem	Language	Result	Execution time	Memory
1070582		AdamGS	Tug of War (BOI15_tug)	C++17	100 / 100	2260 ms	6844 KiB

tug

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(a, b) for(int a = 0; a < (b); ++a)
#define st first
#define nd second
#define pb push_back
#define all(a) a.begin(), a.end()
const int LIM=3e4+7;
vector<int>P;
bitset<LIM*80>B;
vector<pair<int,int>>V[2*LIM];
int F[2*LIM], ile[2*LIM], usun[2*LIM], odw[2*LIM], n, sum, akt;
int fnd(int x) {
	if(F[x]==x) return x;
	return F[x]=fnd(F[x]);
}
void uni(int a, int b) {
	a=fnd(a); b=fnd(b);
	if(a!=b) {
		ile[a]+=ile[b];
		F[b]=a;
	}
	--ile[a];
}
void DFS(int x) {
	odw[x]=1;
	int p=0;
	for(auto i : V[x]) if(!odw[i.st] && !usun[i.st]) {
		++p;
		if(p==2) {
			if(i.st<n) akt+=i.nd; else akt-=i.nd;
		}
	}
	for(auto i : V[x]) if(!odw[i.st] && !usun[i.st]) {
		if(x<n) akt+=i.nd; else akt-=i.nd;
		DFS(i.st);
	}
}
int main() {
	ios_base::sync_with_stdio(0); cin.tie(0);
	int k;
	cin >> n >> k;
	rep(i, 2*n) {
		F[i]=i;
		ile[i]=1;
	}
	rep(i, 2*n) {
		int a, b, c;
		cin >> a >> b >> c; --a; --b; b+=n;
		V[a].pb({b, c});
		V[b].pb({a, c});
		uni(a, b);
	}
	rep(i, 2*n) if(ile[fnd(i)]<0) {
		cout << "NO\n";
		return 0;
	}
	rep(i, 2*n) ile[i]=V[i].size();
	queue<int>q;
	rep(i, 2*n) if(ile[i]==1) q.push(i);
	while(!q.empty()) {
		int p=q.front(); q.pop();
		usun[p]=1;
		for(auto i : V[p]) if(!usun[i.st]) {
			--ile[i.st];
			if(ile[i.st]==1) q.push(i.st);
			if(p<n) sum+=i.nd; else sum-=i.nd;
		}
	}
	rep(i, 2*n) if(!usun[i] && !odw[i]) {
		akt=0;
		DFS(i);
		P.pb(abs(akt));
	}
	sum=abs(sum);
	int S=0;
	B[0]=1;
	for(auto i : P) {
		S+=i;
		B|=B<<i;
	}
	rep(i, 80*LIM) if(B[i]) {
		int a=sum+i, b=S-i;
		if(abs(a-b)<=k) {
			cout << "YES\n";
			return 0;
		}
	}
	cout << "NO\n";
}

• Subtask 1: 18 / 18
• Subtask 2: 30 / 30
• Subtask 3: 23 / 23
• Subtask 4: 29 / 29