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Codeforces Round 943 (Div. 3)/G1. Division + LCP (easy version).cpp

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+/* Problem URL: https://codeforces.com/problemset/problem/1968/G1 */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 1
+
+struct hash_string {
+    static vl p;
+    static ll m;
+    static ll b;
+    vl hash;
+
+    hash_string(string &a) {
+        while (p.size() <= a.size()) {
+            p.push_back(((__int128)p.back() * b) % m);
+        }
+
+        hash.resize(a.size() + 1);
+        rep(i, a.size()) {
+            hash[i + 1] = ((__int128)hash[i] * b + a[i]) % m;
+        }
+    }
+
+    ll gethash(int l, int r) {
+        return ((hash[r + 1] - (__int128)hash[l] * p[r - l + 1]) % m + m) % m;
+    }
+};
+
+vl hash_string::p = {1};
+ll hash_string:: m = (1LL << 61) - 1;
+mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
+ll hash_string:: b = uniform_int_distribution<>()(rng);
+
+void solve()
+{
+    int n, l, r;
+    cin >> n >> l >> r;
+    string a;
+    cin >> a;
+
+    hash_string ah(a);
+
+    int low = 1;
+    int high = n;
+    int ans = 0;
+    while (low <= high) {
+        int mid = (low + high) >> 1;
+
+        int c = 1;
+        for (int i = mid; i + mid - 1 < n; i++) {
+            if (ah.gethash(0, mid - 1) == ah.gethash(i, i + mid - 1)) {
+                c++;
+                i += mid - 1;
+            }
+        }
+
+        if (c >= l) {
+            ans = mid;
+            low = mid + 1;
+            continue;
+        }
+
+        high = mid - 1;
+    }
+
+    cout << ans << '\n';
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}