Submission #532023

#	Time	Username	Problem	Language	Result	Execution time	Memory
532023		Killer2501	Ekoeko (COCI21_ekoeko)	C++14	110 / 110	38 ms	14344 KiB

Main

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define ull unsigned long long
#define pb push_back
#define pll pair<ll, ll>
#define pii pair<ll, int>
#define fi first
#define se second
using namespace std;
const int N = 2e5+2;
const int M = 52;
const int mod = 1e9+7;
const ll base = 75;
const ll inf = 1e16;
int n, lab[N], t, c[N], h[N], m, a[N], b[N], d[N], k;
ll ans;
vector<int> adj[N], g[N];
vector<int> vi;
string s;
bool vis[N];
ll pw(ll k, ll n)
{
    ll total = 1;
    for(; n; n >>= 1)
    {
        if(n&1)total = total * k % mod;
        k = k * k % mod;
    }
    return total;
}
void add(int& x, int y)
{
    x += y;
    if(x >= mod)x -= mod;
}
int findp(int u)
{
    return lab[u] < 0 ? u : lab[u] = findp(lab[u]);
}
void hop(int u, int v)
{
    u = findp(u);
    v = findp(v);
    if(u == v)return;
    if(lab[u] > lab[v])swap(u, v);
    lab[u] += lab[v];
    lab[v] = u;
}
struct BIT
{
    int n;
    vector<ll> fe;
    BIT(){}
    void init(int _n)
    {
        n = _n;
        fe.resize(n+1, 0);
    }
    void reset()
    {
        fill(fe.begin(), fe.end(), 0);
    }
    void add(int id, int x)
    {
        for(; id <= n; id += id & -id)fe[id] += x;
    }
    ll get(int id)
    {
        ll total = 0;
        for(; id; id -= id & -id)total += fe[id];
        return total;
    }
};
void sol()
{
    cin >> n >> s;
    for(int i = 1; i <= n*2; i ++)
        adj[s[i-1]-'a'].pb(i);
    for(int p = 0; p < 26; p ++)
    {
        if(adj[p].empty())continue;
        m = adj[p].size();
        for(int i = 0; i < m/2; i ++)vi.pb(adj[p][i]);
    }
    BIT bit;
    bit.init(n*2);
    sort(vi.begin(), vi.end());
    for(int i = 0; i < n; i ++)
    {
        ans += bit.get(n*2) - bit.get(vi[i]);
        bit.add(vi[i], 1);
        g[s[vi[i]-1]-'a'].pb(i+1);
    }
    vi.clear();
    for(int p = 0; p < 26; p ++)
    {
        if(adj[p].empty())continue;
        m = adj[p].size();
        for(int i = 0; i < m/2; i ++)vi.pb(adj[p][i+m/2]);
    }
    sort(vi.begin(),vi.end());
    for(int i = 0; i < n; i ++)
    {
        ans += bit.get(n*2) - bit.get(vi[i]);
        bit.add(vi[i], 1);
        g[s[vi[i]-1]-'a'].pb(i+n+1);
    }
    for(int i = 0; i < 26; i ++)
    {
        if(g[i].empty())continue;
        m = g[i].size();

        for(int j = m/2; j < m; j ++)
        {
            a[g[i][j]-n] = g[i][j-m/2];
            //cout << g[i][j-m/2] <<" "<< g[i][j]-n << '\n';
        }
    }
    bit.reset();
    for(int i = 1; i <= n; i ++)
    {
        ans += bit.get(n) - bit.get(a[i]);
        bit.add(a[i], 1);
    }
    cout << ans;
}
int main()
{
    cin.tie(0);
    cout.tie(0);
    ios_base::sync_with_stdio(0);
    #define task "test"
    if(fopen(task".inp", "r"))
    {
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    int test = 1;
    //cin >> test;
    while(test -- > 0)sol();
    return 0;
}
/*
1234
21
*/

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:136:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  136 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:137:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  137 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 20 / 20
• Subtask 3: 20 / 20
• Subtask 4: 20 / 20
• Subtask 5: 40 / 40