Submission #1274246

#	Time	Username	Problem	Language	Result	Execution time	Memory
1274246		saleh05	Palindromic Partitions (CEOI17_palindromic)	C++20	0 / 100	1 ms	332 KiB

palindromic

    #include <bits/stdc++.h>
using namespace std ;
#define int long long
#define ll long long
#define FAST ios_base::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
const int MOD = 1e9 + 7  ;
const int INF = 1e18 + 7;
const int MOD2 = 1e9 + 9 ;
/*------------------------------------------------------------------------------------------------------------------------------*/
int dx[] = { -1 , 1 , 0 , 0  };
int dy[] = { 0 , 0 , -1 , 1  };
void flip(int x , int y , vector<string> &s) {
    if (s[x][y] == 'b')s[x][y] = 'w';
    else s[x][y] = 'b';
    for (int i = 0 ; i < 4 ; i++) {
       int nx = x + dx[i] , ny = y + dy[i];
        if (nx >= 0 && nx <4 && ny >= 0 && ny <4) {
            if (s[nx][ny] == 'b')s[nx][ny] = 'w';
            else s[nx][ny] = 'b';
        }

    }
}


void solve() {
// int n ; cin >> n ;
    string s ; cin >> s ;
    int n = s.size() ;
    vector<int> hash(n + 1), pow(n + 1 );
    int p = 109;
    pow[0] = 1 ;
    for (int i = 1 ; i <= n ; i++) {
        hash[i] = (hash[i - 1 ] * p + s[i - 1 ]) % MOD ;
        pow[i] =( pow[i - 1] * p) % MOD ;
    }
    auto compare_s = [&](int l , int r ) -> int {
      return (  hash[r + 1 ] - hash[l] * pow[r - l + 1 ] % MOD + MOD ) % MOD  ;
    };
    int l = 0 , r = n - 1 ;
    int cnt = 0 ;
    while (l <= r ) {
        bool found = false ;
        if (l != r && s[l] == s[r]) {
            cnt += 2 ;
            l++, r--;
            continue ;
        }
        for (int len = 1 ; l !=r - len + 1  &&   len < (r - l + 1) / 2   ; len++) {
            if (compare_s(l , l + len - 1   ) == compare_s(r - len + 1  , r ) ) {
                l+= len ;
                r-= len ;
                cnt+= 2 ;
                found = true;
                break;
            }
        }
        if (!found) {
            cnt+= 1;
            break ;
        }

    }
    cout << cnt << '\n';
}

int32_t main() {
    FAST
#ifndef ONLINE_JUDGE
    freopen("saleh.txt", "r", stdin);
    freopen("out.txt", "w", stdout);
#endif
    int t = 1;
    cin >> t ;
    while (t--) {

        solve();
    }
    return 0;
}

Compilation message (stderr)

palindromic.cpp: In function 'int32_t main()':
palindromic.cpp:70:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   70 |     freopen("saleh.txt", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
palindromic.cpp:71:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   71 |     freopen("out.txt", "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

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