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Submission #895059

# Submission time Handle Problem Language Result Execution time Memory
895059 2023-12-29T11:24:04 Z vjudge1 Palinilap (COI16_palinilap) C++17
100 / 100
 135 ms 30664 KB 
#include <bits/stdc++.h>
using namespace std;

#define int long long
#define F first
#define S second
#define ll long long
#define pb push_back
#define pii pair<int, int>
#define pll pair<ll, unsigned long long>
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define mp make_pair
#define debug cerr << "OK\n";

const int N = (int)1e5 + 5;
const ll mod = (int)1e9 + 9;
const ll mod1 = (int)1e9 + 9;
const ll inf = (int)1e9;
const ll INF = (ll)1e18;
const ll P = 31;

int n;
pll p[N], h[N], q[N];

pll mi(pll a) {
    return {(((-a.F) % mod) + mod) % mod, -a.S};
}

pll add(pll a, pll b) {
    return {(((a.F + b.F) % mod) + mod) % mod, a.S + b.S};
}

pll mul(pll a, pll b) {
    return {(a.F * b.F) % mod, a.S * b.S};
}

pll H(int l, int r) {
    return add(h[r], mi(mul(h[l - 1], p[r - l + 1])));
}

pll Q(int l, int r) {
    return add(q[r], mi(mul(q[l - 1], p[r - l + 1])));
}

bool ipal(int l1, int r1, int l2, int r2) {
    auto [L, R] = mp(n - r2 + 1, n - l2 + 1);
    return H(l1, r1) == Q(L, R);
}

ll us[N], uc[N], cs[N], sc[N], ch[N][27], tmp[N];

void solve() {
    string s;
    cin >> s;
    n = sz(s);
    string t = s;
    reverse(all(t));
    s = '#' + s;
    t = '#' + t;
    p[0] = {1, 1};
    for (int i = 1; i <= n; i++) {
        h[i].F = (h[i - 1].F * P + s[i] - 'a' + 1) % mod;
        h[i].S = (h[i - 1].S * P + s[i] - 'a' + 1);

        q[i].F = (q[i - 1].F * P + t[i] - 'a' + 1) % mod;
        q[i].S = (q[i - 1].S * P + t[i] - 'a' + 1);

        p[i].F = (p[i - 1].F * P) % mod;
        p[i].S = (p[i - 1].S * P);
    }
    int pal = 0;
    for (int i = 1; i <= n; i++) {
        ll l = 1, r = min(i, n - i + 1), mx = 1;
        while (l <= r) {
            int mid = (l + r) / 2;
            if (ipal(i - mid + 1, i + mid - 1, i - mid + 1, i + mid - 1)) {
                l = mid + 1;
                mx = mid;
            } else r = mid - 1;
        }
        pal += mx;
        if (mx > 1) {
        sc[i - mx + 1]++;
        sc[i]--;
        us[i] -= mx - 1;
        cs[i]--;
        cs[i + mx - 1]++;
        uc[i] -= mx - 1;
        }
        if (i - mx > 0 && i + mx <= n) {
            auto [L, R] = mp(i - mx, i + mx);
            l = 2, r = min(L, n - R + 1);
            mx = 1;
            while (l <= r) {
                int mid = (l + r) / 2;
                if (ipal(L - mid + 1, L - 1, R + 1, R + mid - 1)) {
                    l = mid + 1;
                    mx = mid;
                } else r = mid - 1;
            }
            ch[L][s[R] - 'a' + 1] += mx;
            ch[R][s[L] - 'a' + 1] += mx;
        }

        l = 1, r = min(i, n - i), mx = 0;
        while (l <= r) {
            int mid = (l + r) / 2;
            if (ipal(i - mid + 1, i + mid, i - mid + 1, i + mid)) {
                l = mid + 1;
                mx = mid;
            } else r = mid - 1;
        }
        if (mx > 0) {
            pal += mx;
            sc[i - mx + 1]++;
            sc[i + 1]--;
            us[i + 1] -= mx;
            cs[i]--;
            cs[i + mx]++;
            uc[i] -= mx;
        }
        if (i - mx > 0 && i + mx + 1 <= n) {
                auto [L, R] = mp(i - mx, i + mx + 1);
                l = 2, r = min(L, n - R + 1);
                mx = 1;
                while(l <= r) {
                    int mid = (l + r) / 2;
                    if (ipal(L - mid + 1, L - 1, R + 1, R + mid - 1)) {
                        l = mid + 1;
                        mx = mid;
                    } else r = mid - 1;
                }
                ch[L][s[R] - 'a' + 1] += mx;
                ch[R][s[L] - 'a' + 1] += mx;
            }
    }
    sc[n + 1] = cs[n + 1] = 0;
    for (int i = 2; i <= n; i++) {
        sc[i] += sc[i - 1];
    }
    for (int i = 1; i <= n; i++) {
        sc[i] += sc[i - 1] + us[i];
    }
    for (int i = n; i > 0; --i) {
        cs[i] += cs[i + 1];
    }
    for (int i = n; i > 0; --i) {
        cs[i] += cs[i + 1] + uc[i];
    }
    ll ans = pal;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= 26; j++) {
            if (j == s[i] - 'a' + 1) continue;
            ans = max(ans, pal - sc[i] - cs[i] + ch[i][j]);
        }
    }
    cout << ans;
}

signed main() {
    ios_base::sync_with_stdio(0), cin.tie(0);
    int T = 1;
    //cin >> T;
    while (T--) solve();
    return 0;
}

Subtask #1
17.0 / 17.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 8540 KB Output is correct
2 Correct 1 ms 8540 KB Output is correct
3 Correct 1 ms 8788 KB Output is correct
4 Correct 1 ms 8540 KB Output is correct
5 Correct 1 ms 8540 KB Output is correct

Subtask #2
37.0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 8796 KB Output is correct
2 Correct 4 ms 8796 KB Output is correct
3 Correct 4 ms 8796 KB Output is correct
4 Correct 3 ms 8540 KB Output is correct
5 Correct 4 ms 8796 KB Output is correct
6 Correct 6 ms 8796 KB Output is correct
7 Correct 4 ms 8796 KB Output is correct

Subtask #3
46.0 / 46.0

# Verdict Execution time Memory Grader output
1 Correct 102 ms 30292 KB Output is correct
2 Correct 75 ms 30580 KB Output is correct
3 Correct 72 ms 30296 KB Output is correct
4 Correct 117 ms 30244 KB Output is correct
5 Correct 99 ms 30288 KB Output is correct
6 Correct 102 ms 30288 KB Output is correct
7 Correct 100 ms 30412 KB Output is correct
8 Correct 69 ms 9940 KB Output is correct
9 Correct 111 ms 30292 KB Output is correct
10 Correct 100 ms 30292 KB Output is correct
11 Correct 74 ms 30372 KB Output is correct
12 Correct 107 ms 30316 KB Output is correct
13 Correct 111 ms 30292 KB Output is correct
14 Correct 100 ms 30292 KB Output is correct
15 Correct 104 ms 30292 KB Output is correct
16 Correct 89 ms 30416 KB Output is correct
17 Correct 105 ms 30420 KB Output is correct
18 Correct 135 ms 30408 KB Output is correct
19 Correct 106 ms 30664 KB Output is correct