Submission #1076699

#	Time	Username	Problem	Language	Result	Execution time	Memory
1076699		vjudge1	Necklace (Subtask 4) (BOI19_necklace4)	C++17	15 / 15	199 ms	568 KiB

necklace

#include <bits/stdc++.h>
#define all(s) s.begin(), s.end()
#define lb(s, a) lower_bound(all(s), (a)) - s.begin()

using namespace std;

typedef long long ll;

const int ar = 2e5+2;
const ll mod = 1e9+7;
const int oo = 1e9;

vector<int> KMP(string s) {
    int n = (int)s.length();
    vector<int> pi(n);
    for (int i = 1; i < n; i++) {
        int j = pi[i - 1];
        while (j > 0 && s[i] != s[j])
            j = pi[j - 1];
        if (s[i] == s[j])
            j++;
        pi[i] = j;
    }
    return pi;
}

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    #define task "wefwe"
    if(fopen(task".inp", "r")) {
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    string s, t;
    cin >> s >> t;
    int n = s.size(), m = t.size();
    int res = 0, l = 0, r = 0;
    for(int type = 0; type < 2; ++type) {
        reverse(all(s));
        for(int i = 0; i < n; ++i) {
            string s1 = s.substr(0, i + 1), s2 = s.substr(i + 1, n - i - 1);
            reverse(all(s1));
            string tn = t;
            reverse(all(tn));

            vector <int> kmp1 = KMP(s1 + "/" + tn), kmp2 = KMP(s2 + "/" + t);
            for(int j = 0; j < m; ++j) {
                if(res < kmp1[i + m - j] + kmp2[j + n - i]) {
                    res = kmp1[i + m - j] + kmp2[j + n - i];
                    if(type == 0) l = n - i - 1 - kmp2[j + n - i];
                    else l = i + 1 - kmp1[i + m - j];
                    r = j - kmp2[j + n - i] + 1;
                }
            }
        }
    }
    cout << res << '\n' << l << ' ' << r;
}

Compilation message (stderr)

necklace.cpp: In function 'int main()':
necklace.cpp:32:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   32 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
necklace.cpp:33:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   33 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 15 / 15