Submission #887615

#	Time	Username	Problem	Language	Result	Execution time	Memory
887615		Shayan86	Tug of War (BOI15_tug)	C++17	18 / 100	358 ms	4912 KiB

tug

#include <bits/stdc++.h>
using namespace std;

#pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
// Ofast, O0, O1, O2, O3, unroll-loops, fast-math, trapv

typedef long long ll;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;

#define Mp          make_pair
#define sep         ' '
#define endl        '\n'
#define F	        first
#define S	        second
#define pb          push_back
#define all(x)      (x).begin(),(x).end()
#define kill(res)	cout << res << '\n', exit(0);
#define set_dec(x)	cout << fixed << setprecision(x);
#define fast_io     ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define file_io     freopen("input.txt", "r", stdin) ; freopen("output.txt", "w", stdout);

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const ll N = 6e4 + 50;
const ll Mod = 1e9 + 7;

ll n, k, s[N], par[N], h[N], f[N], sum, cnt;
pair<pii, int> edge;

bool mark[N];
vector<ll> vec;
vector<pii> adj[N];

void dfs(int v){
    mark[v] = 1;
    for(auto [u, w]: adj[v]){
        if(u == par[v]) continue;
        else if(mark[u]){
            edge = Mp(Mp(v, u), w);
            continue;
        }
        par[u] = v; h[u] = h[v] + 1; f[u] = w - f[v]; dfs(u);

        if(h[v] % 2) sum += w;
        else sum -= w;
    }
}

const ll M = 10 * N;

bitset<2*M> diff;

void check(int v){
    mark[v] = 1;
    for(auto [u, w]: adj[v]){
        if(!mark[u]) check(u);
    }
    cnt++; sum += adj[v].size();
}

int main(){
    fast_io;

    cin >> n >> k;

    int l, r;
    for(int i = 1; i <= 2*n; i++){
        cin >> l >> r >> s[i]; r += n;
        adj[l].pb(Mp(r, s[i]));
        adj[r].pb(Mp(l, s[i]));
    }

    for(int i = 1; i <= 2*n; i++){
        if(!mark[i]){
            sum = 0; cnt = 0; check(i);
            if(sum != cnt * 2) kill("NO");
        }
    }
    fill(mark, mark + N, 0);

    diff[M] = 1;
    for(int i = 1; i <= 2*n; i++){
        if(!mark[i]){
            sum = 0; dfs(i);
            
            int v = edge.F.F;
            int u = edge.F.S;
            int w = edge.S;

            if(h[v] % 2) sum -= w;
            else sum += w;

            ll sum2 = sum; // f[u] + f[v] - w
            if(h[v] % 2) sum2 -= (f[u] + f[v] - w);
            else sum2 += (f[u] + f[v] - w);
            
            if(sum2 >= 0) diff = diff << sum2;
            else diff = diff >> (-sum2);

            vec.pb(abs(sum - sum2));
            //cout << sum2 << sep << sum - sum2 << endl;
        }
    }

    for(auto x: vec){
        diff = (diff >> x) | (diff << x);
    }

    ll res = Mod;
    for(int i = 0; i < 2*M; i++) if(diff[i]) res = min(res, abs(M-i));

    //cout << res << endl;
    if(res <= k) cout << "YES";
    else cout << "NO";

}

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