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Submission #46179

# Submission time Handle Problem Language Result Execution time Memory
46179 2018-04-17T12:18:49 Z Extazy Palindromes (APIO14_palindrome) C++17
23 / 100
 1000 ms 71320 KB 
#include <bits/stdc++.h>
#define endl '\n'
 
using namespace std;
 
const unsigned long long B1 = 29, B2 = 37;//, MOD = (1e9) + 7;
const int N = 300007;
 
struct rolling_hash {
    unsigned long long h1,h2;
     
    rolling_hash(): h1(0), h2(0) {}
 
    void append(char a) {
        h1*=B1;
        h1+=a-'a'+1;
        h2*=B2;
        h2+=a-'a'+1;
    }
 
    bool operator ==(const rolling_hash &a) const {
        return h1==a.h1 && h2==a.h2;
    }
 
    bool operator <(const rolling_hash &a) const {
        return h1==a.h1 ? h2<a.h2 : h1<a.h1;
    }
};
 
struct hash_rolling_hash {
    unsigned long long operator () (const rolling_hash &a) const {
        return a.h1^(a.h2<<30);
    }
};
 
struct item {
    rolling_hash hash;
    int from,to;
 
    item(){}
    item(rolling_hash a, int b, int c): hash(a), from(b), to(c) {}
    
    bool operator <(const item &a) const {
        return to-from+1==a.to-a.from+1 ? hash<a.hash : to-from+1<a.to-a.from+1;
    }
};
 
int n;
char a[N];
unsigned long long pw1[N],pw2[N];
rolling_hash ph[N],sh[N];
unordered_map < rolling_hash, pair < int, int >, hash_rolling_hash > interval;
unordered_map < rolling_hash, int, hash_rolling_hash > current_cnt;
priority_queue < item > q;
long long ans;
list < item > wait[N];
vector < char > enc;

inline rolling_hash get_prefix_hash(rolling_hash *a, int l, int r) {
    rolling_hash hl=a[l-1],hr=a[r];
 
    hl.h1*=pw1[r-l+1];
    hl.h2*=pw2[r-l+1];
 
    hr.h1-=hl.h1;
    hr.h2-=hl.h2;
    
    return hr;
}
 
inline rolling_hash get_suffix_hash(rolling_hash *a, int l, int r) {
    rolling_hash hl=a[l],hr=a[r+1];
    
    hr.h1*=pw1[r-l+1];
    hr.h2*=pw2[r-l+1];
 
    hl.h1-=hr.h1;
    hl.h2-=hr.h2;
 
    return hl;
}
 
inline bool is_palindrome(int l, int r) {
    return get_prefix_hash(ph,l,r)==get_suffix_hash(sh,l,r);
}
 
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int i,j;
    rolling_hash h;
 
    enc.resize(26);
    for(i=0;i<26;i++) enc[i]='a'+i;

    random_shuffle(enc.begin(),enc.end());
    random_shuffle(enc.begin(),enc.end());

    pw1[0]=pw2[0]=1;
    for(i=1;i<N;i++) {
        pw1[i]=pw1[i-1]*B1;
        pw2[i]=pw2[i-1]*B2;
    }
 
    while((a[++n]=getchar_unlocked())!='\n');
    --n;

    for(i=1;i<=n;i++) a[i]=enc[a[i]-'a'];

    h=rolling_hash();
    for(i=1;i<=n;i++) {
        h.append(a[i]);
        ph[i]=h;
    }
 
    h=rolling_hash();
    for(i=n;i>=1;i--) {
        h.append(a[i]);
        sh[i]=h;
    }
 
    for(i=1;i<=n;i++) {
        int left=0,right=min(i,n-i+1),middle;
 
        while(right-left>1) {
            middle=(left+right)/2;
            
            if(is_palindrome(i-middle,i+middle)) left=middle;
            else right=middle;
        }

        for(j=left;j>=0;j--) {
            h=get_prefix_hash(ph,i-j,i+j);
 
            if(interval.find(h)!=interval.end()) break;
            
            wait[2*j+1].push_back(item(h,i-j,i+j));
            interval[h]=make_pair(i-j,i+j);
        }
 
        h=get_prefix_hash(ph,i-left,i+left);
        ++current_cnt[h];
    }
 
    for(i=1;i<n;i++) if(a[i]==a[i+1]) {
        int left=0,right=min(i,n-i),middle;
        
        while(right-left>1) {
            middle=(left+right)/2;
 
            if(is_palindrome(i-middle,i+1+middle)) left=middle;
            else right=middle;
        }
 
        for(j=left;j>=0;j--) {
            h=get_prefix_hash(ph,i-j,i+1+j);
 
            if(interval.find(h)!=interval.end()) break;
            
            wait[2*j+2].push_back(item(h,i-j,i+1+j));
            interval[h]=make_pair(i-j,i+1+j);
        }
 
        h=get_prefix_hash(ph,i-left,i+1+left);
        ++current_cnt[h];
    }

    for(i=n;i>2;i--) {
        for(item curr: wait[i]) {
            int cnt=current_cnt[curr.hash];
            long long curr_ans=cnt*1ll*i;
            current_cnt.erase(curr.hash);
 
            if(curr_ans>ans) {
                ans=curr_ans;
            }
 
            curr.hash=get_prefix_hash(ph,curr.from+1,curr.to-1);
            pair < int, int > seg=interval[curr.hash];
            curr.from=seg.first;
            curr.to=seg.second;
            current_cnt[curr.hash]+=cnt;
        }
    }
 
    for(;i>=1;i--) {
        for(item curr: wait[i]) { 
            int cnt=current_cnt[curr.hash];
            long long curr_ans=cnt*1ll*i;
 
            if(curr_ans>ans) {
                ans=curr_ans;
            }
        }
    }
 
    printf("%lld\n", ans);
    
    return 0;
}

Subtask #1
8.0 / 8.0

# Verdict Execution time Memory Grader output
1 Correct 17 ms 21496 KB Output is correct
2 Correct 19 ms 21496 KB Output is correct
3 Correct 18 ms 21684 KB Output is correct
4 Correct 18 ms 21684 KB Output is correct
5 Correct 18 ms 21684 KB Output is correct
6 Correct 17 ms 21684 KB Output is correct
7 Correct 16 ms 21692 KB Output is correct
8 Correct 18 ms 21692 KB Output is correct
9 Correct 17 ms 21692 KB Output is correct
10 Correct 18 ms 21708 KB Output is correct
11 Correct 18 ms 21708 KB Output is correct
12 Correct 17 ms 21752 KB Output is correct
13 Correct 19 ms 21752 KB Output is correct
14 Correct 18 ms 21756 KB Output is correct
15 Correct 17 ms 21756 KB Output is correct
16 Correct 17 ms 21756 KB Output is correct
17 Correct 20 ms 21756 KB Output is correct
18 Correct 18 ms 21760 KB Output is correct
19 Correct 17 ms 21760 KB Output is correct
20 Correct 21 ms 21760 KB Output is correct
21 Correct 19 ms 21760 KB Output is correct
22 Correct 18 ms 21848 KB Output is correct
23 Correct 17 ms 21848 KB Output is correct
24 Correct 18 ms 21848 KB Output is correct
25 Correct 19 ms 21848 KB Output is correct
26 Correct 21 ms 21848 KB Output is correct
27 Correct 18 ms 21848 KB Output is correct
28 Correct 16 ms 21848 KB Output is correct
29 Correct 17 ms 21848 KB Output is correct
30 Correct 19 ms 21848 KB Output is correct
31 Correct 17 ms 21848 KB Output is correct
32 Correct 17 ms 21848 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 18 ms 21884 KB Output is correct
2 Correct 25 ms 21884 KB Output is correct
3 Correct 22 ms 21940 KB Output is correct
4 Correct 23 ms 21940 KB Output is correct
5 Correct 19 ms 21940 KB Output is correct
6 Correct 19 ms 22060 KB Output is correct
7 Correct 23 ms 22060 KB Output is correct
8 Correct 18 ms 22060 KB Output is correct
9 Correct 18 ms 22060 KB Output is correct
10 Correct 18 ms 22060 KB Output is correct
11 Correct 18 ms 22060 KB Output is correct
12 Correct 18 ms 22060 KB Output is correct

Subtask #3
0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 27 ms 23296 KB Output is correct
2 Correct 28 ms 23296 KB Output is correct
3 Correct 29 ms 23296 KB Output is correct
4 Correct 28 ms 23304 KB Output is correct
5 Correct 26 ms 23304 KB Output is correct
6 Correct 27 ms 23304 KB Output is correct
7 Correct 28 ms 23304 KB Output is correct
8 Correct 19 ms 23304 KB Output is correct
9 Correct 20 ms 23304 KB Output is correct
10 Incorrect 21 ms 23304 KB Output isn't correct

Subtask #4
0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 217 ms 37660 KB Output is correct
2 Correct 216 ms 37660 KB Output is correct
3 Correct 242 ms 37660 KB Output is correct
4 Correct 246 ms 37788 KB Output is correct
5 Correct 151 ms 37788 KB Output is correct
6 Correct 154 ms 37788 KB Output is correct
7 Correct 184 ms 37788 KB Output is correct
8 Correct 46 ms 37788 KB Output is correct
9 Correct 123 ms 37788 KB Output is correct
10 Incorrect 83 ms 37788 KB Output isn't correct

Subtask #5
0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 789 ms 62676 KB Output is correct
2 Correct 819 ms 63708 KB Output is correct
3 Execution timed out 1008 ms 71320 KB Time limit exceeded
4 Halted 0 ms 0 KB -