Submission #582949

#	Time	Username	Problem	Language	Result	Execution time	Memory
582949		600Mihnea	Palindromic Partitions (CEOI17_palindromic)	C++17	0 / 100	2 ms	340 KiB

palindromic

#include <bits/stdc++.h>

using namespace std;

typedef long double ld;
typedef long long ll;

const int N = (int) 1e6 + 7;
const int INF = (int) 1e9 + 7;
int n;
int a[N];
int dp[N];

bool is_palind(int l, int r) {
  if (l > r) {
    return 1;
  }
  return a[l] == a[r] && is_palind(l + 1, r - 1);
}

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

  freopen ("input.txt", "r", stdin);

  int Tests;
  cin >> Tests;
  for (int tc = 1; tc <= Tests; tc++) {
    {
      string str;
      cin >> str;
      n = (int) str.size();
      int Low = 0, High = n - 1;
      for (int Step = 1; Step <= n; Step++) {
        if (Step % 2 == 0) {
          a[Step] = str[Low++] - 'a';
        } else {
          a[Step] = str[High--] - 'a';
        }
      }
    }

    for (int i = 0; i <= n + 1; i++) {
      dp[i] = -INF;
    }
    dp[0] = 0;
    for (int l = 1; l <= n; l++) {
      for (int r = l; r <= n; r++) {
        bool is = is_palind(l, r);
        if (is && (r - l + 1) % 2 == 0) {
          dp[r] = max(dp[r], dp[l - 1] + 1);
        }
      }
    }
    int sol = 2 * dp[n];
    for (int i = 0; i < n; i++) {
      sol = max(sol, 2 * dp[i] + 1);
    }
    cout << sol << "\n";
  }
}

Compilation message (stderr)

palindromic.cpp: In function 'int main()':
palindromic.cpp:24:11: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   24 |   freopen ("input.txt", "r", stdin);
      |   ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 15
• Subtask 2: 0 / 20
• Subtask 3: 0 / 25
• Subtask 4: 0 / 40