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Submission #46163

# Submission time Handle Problem Language Result Execution time Memory
46163 2018-04-17T11:38:18 Z Extazy Palindromes (APIO14_palindrome) C++17
73 / 100
 1000 ms 70188 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 : 20000;

    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 21 ms 20216 KB Output is correct
2 Correct 17 ms 20324 KB Output is correct
3 Correct 21 ms 20400 KB Output is correct
4 Correct 19 ms 20448 KB Output is correct
5 Correct 18 ms 20524 KB Output is correct
6 Correct 17 ms 20524 KB Output is correct
7 Correct 18 ms 20524 KB Output is correct
8 Correct 18 ms 20552 KB Output is correct
9 Correct 18 ms 20552 KB Output is correct
10 Correct 18 ms 20552 KB Output is correct
11 Correct 17 ms 20680 KB Output is correct
12 Correct 18 ms 20680 KB Output is correct
13 Correct 18 ms 20680 KB Output is correct
14 Correct 17 ms 20680 KB Output is correct
15 Correct 17 ms 20680 KB Output is correct
16 Correct 18 ms 20680 KB Output is correct
17 Correct 17 ms 20728 KB Output is correct
18 Correct 17 ms 20728 KB Output is correct
19 Correct 18 ms 20728 KB Output is correct
20 Correct 18 ms 20728 KB Output is correct
21 Correct 18 ms 20728 KB Output is correct
22 Correct 17 ms 20728 KB Output is correct
23 Correct 17 ms 20728 KB Output is correct
24 Correct 21 ms 20728 KB Output is correct
25 Correct 18 ms 20728 KB Output is correct
26 Correct 17 ms 20728 KB Output is correct
27 Correct 18 ms 20728 KB Output is correct
28 Correct 18 ms 20728 KB Output is correct
29 Correct 17 ms 20728 KB Output is correct
30 Correct 22 ms 20728 KB Output is correct
31 Correct 18 ms 20728 KB Output is correct
32 Correct 21 ms 20728 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 20 ms 20732 KB Output is correct
2 Correct 18 ms 20732 KB Output is correct
3 Correct 18 ms 20732 KB Output is correct
4 Correct 19 ms 20732 KB Output is correct
5 Correct 18 ms 20732 KB Output is correct
6 Correct 19 ms 20732 KB Output is correct
7 Correct 18 ms 20732 KB Output is correct
8 Correct 18 ms 20732 KB Output is correct
9 Correct 39 ms 20732 KB Output is correct
10 Correct 17 ms 20732 KB Output is correct
11 Correct 17 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 30 ms 22268 KB Output is correct
2 Correct 28 ms 22268 KB Output is correct
3 Correct 39 ms 22268 KB Output is correct
4 Correct 30 ms 22268 KB Output is correct
5 Correct 33 ms 22268 KB Output is correct
6 Correct 26 ms 22268 KB Output is correct
7 Correct 28 ms 22268 KB Output is correct
8 Correct 20 ms 22268 KB Output is correct
9 Correct 20 ms 22268 KB Output is correct
10 Correct 24 ms 22268 KB Output is correct

Subtask #4
26.0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 217 ms 36384 KB Output is correct
2 Correct 241 ms 36384 KB Output is correct
3 Correct 269 ms 36504 KB Output is correct
4 Correct 285 ms 36664 KB Output is correct
5 Correct 165 ms 36664 KB Output is correct
6 Correct 137 ms 36664 KB Output is correct
7 Correct 215 ms 36664 KB Output is correct
8 Correct 52 ms 36664 KB Output is correct
9 Correct 77 ms 36664 KB Output is correct
10 Correct 135 ms 36664 KB Output is correct

Subtask #5
0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 739 ms 61408 KB Output is correct
2 Correct 786 ms 62672 KB Output is correct
3 Execution timed out 1020 ms 70188 KB Time limit exceeded
4 Halted 0 ms 0 KB -