Submission #890757

#	Time	Username	Problem	Language	Result	Execution time	Memory
890757		zeta7532	Tug of War (BOI15_tug)	C++17	41 / 100	124 ms	1880 KiB

tug

#include <bits/stdc++.h>
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
using namespace std;
using ll = long long;
const ll mod = 998244353;
#define fi first
#define se second
#define rep(i,n) for(ll i=0;i<n;i++)
#define all(x) x.begin(),x.end()
#define faster ios::sync_with_stdio(false);cin.tie(nullptr)

struct unionfind{
  	unionfind() {}
    vector<ll> par,sz;
    unionfind(ll n):par(n),sz(n){
        for(ll i=0;i<n;i++) par[i]=i, sz[i]=1;
    }
    ll root(ll x){
        if(par[x]==x) return x;
        ll t=root(par[x]);
        par[x]=t;
        return t;
    }
    ll size(ll x){
        return sz[x];
    }
    void unite(ll x,ll y){
        ll rx=root(x);
        ll ry=root(y);
        if(rx==ry) return;
        if (sz[rx]>sz[ry]) swap(rx,ry);
        par[rx]=ry;sz[ry]+=sz[rx];
    }
    bool same(ll x,ll y){
        ll rx=root(x);
        ll ry=root(y);
        return rx==ry;
    }
};

int main() {
    ll N,K;
    cin >> N >> K;
    N*=2;
    vector<ll> l(N),r(N),s(N);
    ll max_s=0;
    rep(i,N){
        cin >> l[i] >> r[i] >> s[i];
        l[i]--,r[i]--;
        max_s=max(max_s,s[i]);
    }
    if(N<=20){
        bool ans=false;
        rep(bit,1<<N){
            vector<ll> L(N/2,-1),R(N/2,-1);
            rep(i,N){
                if(bit&(1<<i)) L[l[i]]=i;
                else R[r[i]]=i;
            }
            ll cnt_l=0,cnt_r=0;
            rep(i,N/2){
                if(L[i]==-1){
                    cnt_l=-1;
                    break;
                }
                cnt_l+=s[L[i]];
            }
            rep(i,N/2){
                if(R[i]==-1){
                    cnt_r=-1;
                    break;
                }
                cnt_r+=s[R[i]];
            }
            if(cnt_l==-1||cnt_r==-1) continue;
            if(abs(cnt_l-cnt_r)<=K) ans=true;
        }
        if(ans) cout << "YES" << endl;
        else cout << "NO" << endl;
        return 0;
    }
    if(max_s==1){
        unionfind tree(N);
        rep(i,N) tree.unite(l[i],r[i]+N/2);
        vector<ll> cnt(N,0);
        rep(i,N) cnt[tree.root(l[i])]++;
        bool ans=true;
        rep(i,N){
            if(tree.root(i)!=i) continue;
            if(cnt[i]!=tree.size(i)) ans=false;
        }
        if(ans) cout << "YES" << endl;
        else cout << "NO" << endl;
        return 0;
    }
    return 0;
}

• Subtask 1: 18 / 18
• Subtask 2: 0 / 30
• Subtask 3: 23 / 23
• Subtask 4: 0 / 29