Submission #1096069

#	Time	Username	Problem	Language	Result	Execution time	Memory
1096069		cpptowin	Tug of War (BOI15_tug)	C++17	100 / 100	587 ms	36248 KiB

tug

#include <bits/stdc++.h>
#define fo(i, d, c) for (int i = d; i <= c; i++)
#define fod(i, c, d) for (int i = c; i >= d; i--)
#define maxn 600010
#define N 1010
#define fi first
#define se second
#define pb emplace_back
#define en cout << "\n";
#define bitcount(x) __builtin_popcountll(x)
#define pii pair<int, int>
#define vii vector<pii>
#define lb(x) x & -x
#define bit(i, j) ((i >> j) & 1)
#define offbit(i, j) (i ^ (1LL << j))
#define onbit(i, j) (i | (1LL << j))
#define vi vector<int>
#define all(x) x.begin(), x.end()
#define ss(x) (int)x.size()
template <typename T1, typename T2>
bool minimize(T1 &a, T2 b)
{
    if (a > b)
    {
        a = b;
        return true;
    }
    return false;
}
template <typename T1, typename T2>
bool maximize(T1 &a, T2 b)
{
    if (a < b)
    {
        a = b;
        return true;
    }
    return false;
}
using namespace std;
const int nsqrt = 450;
const int mod = 1e9 + 7;
void add(int &x, int k)
{
    x += k;
    x %= mod;
    if (x < 0)
        x += mod;
}
void del(int &x, int k)
{
    x -= k;
    x %= mod;
    if (x < 0)
        x += mod;
}
int cnt[maxn];
bool ok[maxn];
array<int, 3> edge[maxn];
int n, k;
set<int> ke[maxn];
vi things;
int total = 0;
int sum;
void dfs(int u, int val)
{
    if(ke[u].empty()) 
    {
        if(sum != 0)
        things.pb(abs(sum));
        return;
    }
    auto [i,j,w] = edge[*ke[u].begin()];
    int v = i + j - u;
    sum += w * val;
    ke[v].erase(ke[v].find(*ke[u].begin()));
    ke[u].erase(ke[u].begin());
    dfs(v,-val);
}
bitset<600010> f;
main()
{
#define name "TASK"
    if (fopen(name ".inp", "r"))
    {
        freopen(name ".inp", "r", stdin);
        freopen(name ".out", "w", stdout);
    }
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cin >> n >> k;
    fo(i, 1, 2 * n)
    {
        int u, v, w;
        cin >> u >> v >> w;
        edge[i] = {u, v + n, w};
        ke[u].insert(i);
        ke[v + n].insert(i);
        ok[i] = 1;
    }
    queue<int> q;
    fo(i,1,2 * n) 
    {
        if(ss(ke[i]) == 0) return cout << "NO",0;
        if(ss(ke[i]) == 1) q.push(i);
    }
    while(ss(q))
    {
        int u = q.front();
        q.pop();
        if(ss(ke[u]) == 0) return cout << "NO",0;
        int it = *ke[u].begin();
        int v = edge[it][0] + edge[it][1] - u;
        if(v > n) sum -= edge[it][2];
        else sum += edge[it][2];
        ke[u].clear();
        ke[v].erase(ke[v].find(it));
        if(ss(ke[v]) == 1) q.push(v);
    }
    if(sum != 0)
    things.pb(abs(sum));
    fo(i, 1, 2 * n) if (ss(ke[i]))
    {
        sum = 0;
        dfs(i, 1);
    }
    total = accumulate(all(things),0);
    f[0] = 1;
    for (int it : things)
        f |= f << it;
    fo(i, 0, 600000) if (f[i] and abs(total - 2 * i) <= k) return cout << "YES", 0;
    cout << "NO";
}

Compilation message (stderr)

tug.cpp:81:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   81 | main()
      | ^~~~
tug.cpp: In function 'int main()':
tug.cpp:86:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   86 |         freopen(name ".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
tug.cpp:87:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   87 |         freopen(name ".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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