Submission #871670

#	Time	Username	Problem	Language	Result	Execution time	Memory
871670		vjudge1	Difference (POI11_roz)	C++17	60 / 100	1093 ms	11200 KiB

roz

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

const int maxn = 1e6+55;
const int inf = 1e9+55;

typedef pair <int,int> pii;

int a[maxn], b[maxn];
int cnt[maxn], n;
int pref[maxn], cntPref[maxn];

int brute()
{
    int best = 0;
    for (int i = 1; i <= n; i ++)
    {
        multiset <int> st;
        for (int c = 0; c < 26; c ++) cnt[c] = 0;

        int mx = 0;
        for (int j = i; j <= n; j ++)
        {
            int c = a[j];
            if (st.find(cnt[c]) != st.end()) st.erase(st.find(cnt[c]));
            cnt[c] ++;
            st.insert(cnt[c]);

            int delta = abs(*(st.begin()) - *(--st.end()));
            best = max(best, delta);
        }
    }

    return best;
}

bool check(int l, int r)
{
    if (!l) return r > 0;
    return cntPref[r] - cntPref[l-1];
}

int cal(int c1, int c2)
{
    vector <int> rem;
    rem.push_back(0);
    for (int i = 1; i <= n; i ++)
    {
        if (a[i] == c1)
            rem.push_back(1);
        else if (a[i] == c2)
            rem.push_back(-1);
    }

    int m = rem.size() - 1;
    for (int i = 1; i <= m; i ++) cntPref[i] = cntPref[i-1] + (rem[i] == -1);
    for (int i = 1; i <= m; i ++) pref[i] = pref[i-1] + rem[i];

    int j = 0, mn = inf, best = 0;
    for (int i = 1; i <= m; i ++)
    {
        while (j < i && cntPref[i] - cntPref[j] > 0)
        {
            mn = min(mn, pref[j]);
            j ++;
        }
        best = max(best, pref[i] - mn);
    }
    return best;
}

void process()
{
    cin >> n;
    for (int i = 1; i <= n; i ++)
    {
        char x;
        cin >> x;
        a[i] = x - 'a';
    }

    int best = 0;
    for (int c1 = 0; c1 < 26; c1 ++) for (int c2 = 0; c2 < 26; c2 ++) if (c1 != c2)
    {
        best = max(best, cal(c1, c2));
//        cout << c1 << " " << c2 << " " << best << endl;
    }
//    cout << brute() << endl;
    cout << best;
}

signed main()
{
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);

    int ntest = 1;
    while (ntest --) process();

    return 0;
}

Compilation message (stderr)

roz.cpp: In function 'int brute()':
roz.cpp:23:13: warning: unused variable 'mx' [-Wunused-variable]
   23 |         int mx = 0;
      |             ^~

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 10 / 10
• Subtask 5: 10 / 10
• Subtask 6: 10 / 10
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10
• Subtask 10: 0 / 10