oj.uz

Submission #46160

# Submission time Handle Problem Language Result Execution time Memory
46160 2018-04-17T11:36:43 Z Extazy Palindromes (APIO14_palindrome) C++17
73 / 100
 687 ms 62412 KB 
#include <bits/stdc++.h>
#define endl '\n'
 
using namespace std;
 
const unsigned long long B1 = 131, B2 = 137, MOD = (1e9) + 7;
const int N = 300007;
 
struct rolling_hash {
    unsigned long long h1;
    unsigned h2;
    
    rolling_hash(): h1(0), h2(0) {}
 
    void append(char a) {
        h1*=B1;
        h1+=a-'a'+1;
        h2=(h2*1llu*B2+a-'a'+1)%MOD;
    }
 
    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];
unsigned 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];
 
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=hl.h2*1llu*pw2[r-l+1]%MOD;
 
    hr.h1-=hl.h1;
    hr.h2-=hl.h2;
    hr.h2+=MOD;
    hr.h2%=MOD;
    
    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=hr.h2*1llu*pw2[r-l+1]%MOD;
 
    hl.h1-=hr.h1;
    hl.h2-=hr.h2;
    hl.h2+=MOD;
    hl.h2%=MOD;
 
    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;
 
    pw1[0]=pw2[0]=1;
    for(i=1;i<N;i++) {
        pw1[i]=pw1[i-1]*B1;
        pw2[i]=pw2[i-1]*1llu*B2%MOD;
    }
 
    while((a[++n]=getchar_unlocked())!='\n');
    --n;
 
    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];
    }
 
    int T = n<=100000 ? 2 : 100000;

    for(i=n;i>T;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;
        }
    }
 
    if(n<=100000) 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 22 ms 20216 KB Output is correct
2 Correct 18 ms 20324 KB Output is correct
3 Correct 18 ms 20400 KB Output is correct
4 Correct 17 ms 20436 KB Output is correct
5 Correct 18 ms 20436 KB Output is correct
6 Correct 18 ms 20564 KB Output is correct
7 Correct 18 ms 20564 KB Output is correct
8 Correct 17 ms 20564 KB Output is correct
9 Correct 18 ms 20580 KB Output is correct
10 Correct 17 ms 20580 KB Output is correct
11 Correct 17 ms 20580 KB Output is correct
12 Correct 18 ms 20588 KB Output is correct
13 Correct 18 ms 20588 KB Output is correct
14 Correct 19 ms 20588 KB Output is correct
15 Correct 18 ms 20716 KB Output is correct
16 Correct 18 ms 20716 KB Output is correct
17 Correct 17 ms 20716 KB Output is correct
18 Correct 19 ms 20716 KB Output is correct
19 Correct 18 ms 20716 KB Output is correct
20 Correct 17 ms 20716 KB Output is correct
21 Correct 17 ms 20716 KB Output is correct
22 Correct 18 ms 20716 KB Output is correct
23 Correct 17 ms 20716 KB Output is correct
24 Correct 17 ms 20716 KB Output is correct
25 Correct 17 ms 20716 KB Output is correct
26 Correct 17 ms 20716 KB Output is correct
27 Correct 17 ms 20716 KB Output is correct
28 Correct 19 ms 20716 KB Output is correct
29 Correct 18 ms 20716 KB Output is correct
30 Correct 18 ms 20716 KB Output is correct
31 Correct 17 ms 20716 KB Output is correct
32 Correct 18 ms 20716 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 19 ms 20732 KB Output is correct
2 Correct 18 ms 20732 KB Output is correct
3 Correct 19 ms 20732 KB Output is correct
4 Correct 18 ms 20732 KB Output is correct
5 Correct 18 ms 20732 KB Output is correct
6 Correct 18 ms 20732 KB Output is correct
7 Correct 19 ms 20732 KB Output is correct
8 Correct 19 ms 20732 KB Output is correct
9 Correct 18 ms 20732 KB Output is correct
10 Correct 18 ms 20732 KB Output is correct
11 Correct 23 ms 20732 KB Output is correct
12 Correct 18 ms 20732 KB Output is correct

Subtask #3
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 29 ms 22140 KB Output is correct
2 Correct 28 ms 22140 KB Output is correct
3 Correct 30 ms 22140 KB Output is correct
4 Correct 30 ms 22140 KB Output is correct
5 Correct 26 ms 22140 KB Output is correct
6 Correct 27 ms 22140 KB Output is correct
7 Correct 29 ms 22140 KB Output is correct
8 Correct 20 ms 22140 KB Output is correct
9 Correct 21 ms 22140 KB Output is correct
10 Correct 24 ms 22140 KB Output is correct

Subtask #4
26.0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 236 ms 36504 KB Output is correct
2 Correct 204 ms 36504 KB Output is correct
3 Correct 273 ms 36508 KB Output is correct
4 Correct 259 ms 36508 KB Output is correct
5 Correct 151 ms 36508 KB Output is correct
6 Correct 133 ms 36508 KB Output is correct
7 Correct 229 ms 36508 KB Output is correct
8 Correct 47 ms 36508 KB Output is correct
9 Correct 78 ms 36508 KB Output is correct
10 Correct 142 ms 36508 KB Output is correct

Subtask #5
0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 687 ms 61344 KB Output is correct
2 Incorrect 618 ms 62412 KB Output isn't correct
3 Halted 0 ms 0 KB -