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Submission #915730

# Submission time Handle Problem Language Result Execution time Memory
915730 2024-01-24T15:52:03 Z aykhn Palindromic Partitions (CEOI17_palindromic) C++17
100 / 100
 224 ms 36252 KB 
#include <bits/stdc++.h>

// author: aykhn

using namespace std;
typedef long long ll;

#define int long long
#define inf 0x3F3F3F3F3F3F3F3F

const int mod = 1e9 + 7;
const int MXN = 1e6 + 1;
const int base = 12031;

int ph[MXN], p[MXN], invp[MXN];

int mult(int a, int b)
{
    return (a * b) % mod;
}

int add(int a, int b)
{
    return (a + b) % mod;
}

int pw(int a, int b, int c)
{
    a %= c;
    int res = 1;
    while (b)
    {
        if (b & 1) res = mult(res, a);
        a = mult(a, a);
        b >>= 1;
    }
    return res;
}

int get_hash(int l, int r)
{
    return mult(add(ph[r], mod - ph[l - 1]), invp[l]);
}

void _()
{
    string s;
    cin >> s;
    int n = s.length();
    s = "#" + s;
    ph[0] = 0;
    for (int i = 1; i <= n; i++) ph[i] = add(ph[i - 1], mult(p[i], s[i] - 'a'));
    int res = 0;
    int f = 1;
    int l = 1;
    int r = n;
    for (int i = 1; i <= n/2; i++)
    {
        if (get_hash(l, i) == get_hash(n - i + 1, r)) 
        {
            l = i + 1;
            r = n - i;
            res++;
        }
    }
    
    cout << res * 2 + (l <= r) << '\n';
}

signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(nullptr);
    p[0] = 1;
    for (int i = 1; i < MXN; i++) p[i] = mult(p[i - 1], base);
    for (int i = 0; i < MXN; i++) invp[i] = pw(p[i], mod - 2, mod);
    int t = 1;
    cin >> t;
    for (int tt = 1; tt <= t; tt++)
    {
        _();
    }
}

Compilation message

palindromic.cpp: In function 'void _()':
palindromic.cpp:54:9: warning: unused variable 'f' [-Wunused-variable]
   54 |     int f = 1;
      |         ^

Subtask #1
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 121 ms 16976 KB Output is correct
2 Correct 120 ms 17036 KB Output is correct
3 Correct 120 ms 17032 KB Output is correct
4 Correct 119 ms 16980 KB Output is correct
5 Correct 120 ms 17036 KB Output is correct

Subtask #2
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 121 ms 16976 KB Output is correct
2 Correct 120 ms 17036 KB Output is correct
3 Correct 120 ms 17032 KB Output is correct
4 Correct 119 ms 16980 KB Output is correct
5 Correct 120 ms 17036 KB Output is correct
6 Correct 120 ms 17040 KB Output is correct
7 Correct 119 ms 17024 KB Output is correct
8 Correct 120 ms 16980 KB Output is correct
9 Correct 120 ms 17020 KB Output is correct

Subtask #3
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 121 ms 16976 KB Output is correct
2 Correct 120 ms 17036 KB Output is correct
3 Correct 120 ms 17032 KB Output is correct
4 Correct 119 ms 16980 KB Output is correct
5 Correct 120 ms 17036 KB Output is correct
6 Correct 120 ms 17040 KB Output is correct
7 Correct 119 ms 17024 KB Output is correct
8 Correct 120 ms 16980 KB Output is correct
9 Correct 120 ms 17020 KB Output is correct
10 Correct 121 ms 17232 KB Output is correct
11 Correct 120 ms 16980 KB Output is correct
12 Correct 121 ms 16976 KB Output is correct
13 Correct 121 ms 17020 KB Output is correct

Subtask #4
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 121 ms 16976 KB Output is correct
2 Correct 120 ms 17036 KB Output is correct
3 Correct 120 ms 17032 KB Output is correct
4 Correct 119 ms 16980 KB Output is correct
5 Correct 120 ms 17036 KB Output is correct
6 Correct 120 ms 17040 KB Output is correct
7 Correct 119 ms 17024 KB Output is correct
8 Correct 120 ms 16980 KB Output is correct
9 Correct 120 ms 17020 KB Output is correct
10 Correct 121 ms 17232 KB Output is correct
11 Correct 120 ms 16980 KB Output is correct
12 Correct 121 ms 16976 KB Output is correct
13 Correct 121 ms 17020 KB Output is correct
14 Correct 224 ms 36252 KB Output is correct
15 Correct 177 ms 31232 KB Output is correct
16 Correct 218 ms 35472 KB Output is correct
17 Correct 177 ms 27676 KB Output is correct