Submission #1155256

#	Time	Username	Problem	Language	Result	Execution time	Memory
1155256		nathan4690	Necklace (Subtask 4) (BOI19_necklace4)	C++20	15 / 15	848 ms	2824 KiB

necklace

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define f1(i,n) for(int i=1;i<=n;i++)
#define __file_name ""
using namespace std;
const ll maxn = 1e6+5, inf=1e18;

struct Result{
    int len, i, j;
    Result(int len=0, int i=0, int j=0): len(len), i(i), j(j){};
    bool operator<(const Result &rhs) const{
        return len < rhs.len;
    }
};

int n, m;
string s, t;
vector<int> outs[3005];
priority_queue<int, vector<int>, greater<int>> pq;
bool del[3005];

Result solve(){
    Result ans;
    for(int pos=0;pos<m;pos++){
        string pref = t.substr(0, pos+1), suff = t.substr(pos+1, m);
        string p = suff + '#' + s;
        int sz = p.size();
        vector<int> z(sz, 0);
        for (int i = 1, l = 0, r = 0; i < sz; ++i) {
            if (i <= r)
                z[i] = min(r - i + 1, z[i - l]);
            while (i + z[i] < sz && p[z[i]] == p[i + z[i]])
                ++z[i];
            if (i + z[i] - 1 > r) {
                l = i;
                r = i + z[i] - 1;
            }
        }
        reverse(z.begin(), z.end());
        z.resize(n);
        reverse(z.begin(), z.end());
        reverse(pref.begin(), pref.end());
        p = s; reverse(p.begin(), p.end());
        p = pref + '#' + p;
        sz = p.size();
        vector<int> pi(sz, 0);
        for (int i = 1; i < sz; i++) {
            int j = pi[i - 1];
            while (j > 0 && p[i] != p[j])
                j = pi[j - 1];
            if (p[i] == p[j])
                j++;
            pi[i] = j;
        }
        reverse(pi.begin(), pi.end());
        pi.resize(n);
        for(int i=0;i<=n;i++) {
            outs[i].clear();
            del[i] = 0;
        }
        while(!pq.empty()) pq.pop();
        for(int i=0;i<n;i++){
            for(int item: outs[i]){
                del[item] = true;
            }
            while(!pq.empty()){
                int j = pq.top();
                if(del[j]) pq.pop();
                else break;
            }
            if(!pq.empty()){
                int j = pq.top();
                ans = max(ans, Result(pi[i] + i - j, j, pos - pi[i] + 1));
            }else {
                ans = max(ans, Result(pi[i], i, pos - pi[i] + 1));
            }
            if(z[i]){
                pq.push(i);
                outs[i + z[i] + 1].push_back(i);
            }
        }
//        if(pos == 92){
//            cout << pref << '\n' << suff << '\n';
//            cout << s << ' ' << t << ' ' << pos << '\n';
//            for(int item: pi) cout << item << ' '; cout << '\n';
//            for(int item: z) cout << item << ' '; cout << '\n';
//        }
    }
    return ans;
}

int main(){
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);

    if(fopen(__file_name ".inp", "r")){
        freopen(__file_name ".inp","r",stdin);
        freopen(__file_name ".out","w",stdout);
    }
    cin >> s >> t;
    n = s.size(); m = t.size();
    Result res1 = solve();
    reverse(t.begin(), t.end());
    Result res2 = solve();
    res2.j = m - 1 - (res2.j + res2.len - 1);
    res1 = max(res1, res2);
    cout << res1.len << '\n' << res1.i << ' ' << res1.j << '\n';
    return 0;
}

Compilation message (stderr)

necklace.cpp: In function 'int main()':
necklace.cpp:97:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   97 |         freopen(__file_name ".inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
necklace.cpp:98:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   98 |         freopen(__file_name ".out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 15 / 15