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Submission #46168

# Submission time Handle Problem Language Result Execution time Memory
46168 2018-04-17T11:41:26 Z Extazy Palindromes (APIO14_palindrome) C++17
73 / 100
 1000 ms 70164 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;
const int P = 200000;

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<=P ? 2 : 40000;

    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<=P) 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 18 ms 20344 KB Output is correct
2 Correct 18 ms 20344 KB Output is correct
3 Correct 18 ms 20532 KB Output is correct
4 Correct 18 ms 20532 KB Output is correct
5 Correct 22 ms 20532 KB Output is correct
6 Correct 23 ms 20636 KB Output is correct
7 Correct 18 ms 20636 KB Output is correct
8 Correct 18 ms 20636 KB Output is correct
9 Correct 21 ms 20636 KB Output is correct
10 Correct 19 ms 20636 KB Output is correct
11 Correct 18 ms 20636 KB Output is correct
12 Correct 21 ms 20636 KB Output is correct
13 Correct 18 ms 20636 KB Output is correct
14 Correct 17 ms 20636 KB Output is correct
15 Correct 17 ms 20636 KB Output is correct
16 Correct 19 ms 20636 KB Output is correct
17 Correct 18 ms 20636 KB Output is correct
18 Correct 19 ms 20636 KB Output is correct
19 Correct 18 ms 20636 KB Output is correct
20 Correct 23 ms 20636 KB Output is correct
21 Correct 19 ms 20636 KB Output is correct
22 Correct 18 ms 20636 KB Output is correct
23 Correct 18 ms 20636 KB Output is correct
24 Correct 22 ms 20636 KB Output is correct
25 Correct 18 ms 20636 KB Output is correct
26 Correct 18 ms 20636 KB Output is correct
27 Correct 20 ms 20636 KB Output is correct
28 Correct 18 ms 20636 KB Output is correct
29 Correct 18 ms 20636 KB Output is correct
30 Correct 18 ms 20636 KB Output is correct
31 Correct 18 ms 20636 KB Output is correct
32 Correct 19 ms 20636 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 21 ms 20732 KB Output is correct
2 Correct 18 ms 20736 KB Output is correct
3 Correct 21 ms 20772 KB Output is correct
4 Correct 18 ms 20772 KB Output is correct
5 Correct 19 ms 20772 KB Output is correct
6 Correct 19 ms 20772 KB Output is correct
7 Correct 23 ms 20772 KB Output is correct
8 Correct 19 ms 20772 KB Output is correct
9 Correct 19 ms 20772 KB Output is correct
10 Correct 18 ms 20772 KB Output is correct
11 Correct 18 ms 20772 KB Output is correct
12 Correct 19 ms 20772 KB Output is correct

Subtask #3
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 29 ms 22144 KB Output is correct
2 Correct 32 ms 22144 KB Output is correct
3 Correct 37 ms 22268 KB Output is correct
4 Correct 33 ms 22268 KB Output is correct
5 Correct 26 ms 22268 KB Output is correct
6 Correct 26 ms 22268 KB Output is correct
7 Correct 32 ms 22268 KB Output is correct
8 Correct 21 ms 22268 KB Output is correct
9 Correct 20 ms 22268 KB Output is correct
10 Correct 30 ms 22268 KB Output is correct

Subtask #4
26.0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 246 ms 36376 KB Output is correct
2 Correct 242 ms 36376 KB Output is correct
3 Correct 283 ms 36672 KB Output is correct
4 Correct 291 ms 36672 KB Output is correct
5 Correct 164 ms 36672 KB Output is correct
6 Correct 134 ms 36672 KB Output is correct
7 Correct 205 ms 36672 KB Output is correct
8 Correct 47 ms 36672 KB Output is correct
9 Correct 79 ms 36672 KB Output is correct
10 Correct 147 ms 36672 KB Output is correct

Subtask #5
0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 738 ms 61672 KB Output is correct
2 Correct 704 ms 62568 KB Output is correct
3 Execution timed out 1047 ms 70164 KB Time limit exceeded
4 Halted 0 ms 0 KB -