Submission #209275

#	Time	Username	Problem	Language	Result	Execution time	Memory
209275		stefdasca	Tug of War (BOI15_tug)	C++14	100 / 100	2102 ms	11256 KiB

tug

#include<bits/stdc++.h>
#define pb push_back
#define fi first
#define se second
using namespace std;

int n, maxdif, skill[60002];
set<int> v[60002];

pair<int, int> vals[60002];
bool viz[60002];

int dif;

bitset<20 * 60002> dp;
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cin >> n >> maxdif;
    for(int i = 1; i <= n+n; ++i)
    {
        int a, b;
        cin >> a >> b >> skill[i];
        b += n;
        v[a].insert(i);
        v[b].insert(i);
        vals[i] = {a, b};
    }
    deque<int> d;
    for(int i = 1; i <= n+n; ++i)
        if(v[i].size() < 2)
            d.pb(i), viz[i] = 1;
    while(!d.empty())
    {
        int poz = d[0];
        d.pop_front();
        if(v[poz].size() == 0)
        {
            cout << "NO\n";
            return 0;
        }
        int nr = *v[poz].begin();
        v[vals[nr].fi].erase(nr);
        v[vals[nr].se].erase(nr);
        if(v[vals[nr].fi].size() < 2 && !viz[vals[nr].fi])
        {
            viz[vals[nr].fi] = 1;
            d.pb(vals[nr].fi);
        }
        if(v[vals[nr].se].size() < 2 && !viz[vals[nr].se])
        {
            viz[vals[nr].se] = 1;
            d.pb(vals[nr].se);
        }
        if(poz <= n)
            dif += skill[nr];
        else
            dif -= skill[nr];
    }
    vector<int> ruk;
    for(int i = 1; i <= n+n; ++i)
    {
        if(v[i].size() < 2)
            continue;
        int valas = 0;
        int j = i;
        while(v[j].size())
        {
            int val = *v[j].begin();
            if(j <= n)
                valas += skill[val];
            else
                valas -= skill[val];
            v[vals[val].fi].erase(val);
            v[vals[val].se].erase(val);
            if(j == vals[val].fi)
                j = vals[val].se;
            else
                j = vals[val].fi;
        }
        valas = abs(valas);
        dif -= valas;
        ruk.pb(2 * valas);
    }
    dif += 20 * n;
    dp[dif] = 1;
    for(int i = 0; i < ruk.size(); ++i)
        dp = dp | (dp << ruk[i]);
    bool ok = 0;
    for(int i = 20 * n - maxdif; i <= 20 * n + maxdif; ++i)
        ok |= dp[i];
    if(ok)
        cout << "YES\n";
    else
        cout << "NO\n";
    return 0;
}

Compilation message (stderr)

tug.cpp: In function 'int main()':
tug.cpp:88:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0; i < ruk.size(); ++i)
                    ~~^~~~~~~~~~~~

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