oj.uz

Submission #46177

# Submission time Handle Problem Language Result Execution time Memory
46177 2018-04-17T12:15:54 Z Extazy Palindromes (APIO14_palindrome) C++17
23 / 100
 1000 ms 70964 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,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());

    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;
        }

        if(n>100000 && left<10000) continue;
 
        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 19 ms 21496 KB Output is correct
2 Correct 19 ms 21496 KB Output is correct
3 Correct 20 ms 21640 KB Output is correct
4 Correct 19 ms 21640 KB Output is correct
5 Correct 19 ms 21640 KB Output is correct
6 Correct 19 ms 21712 KB Output is correct
7 Correct 18 ms 21836 KB Output is correct
8 Correct 18 ms 21836 KB Output is correct
9 Correct 18 ms 21972 KB Output is correct
10 Correct 17 ms 21972 KB Output is correct
11 Correct 18 ms 21972 KB Output is correct
12 Correct 21 ms 21972 KB Output is correct
13 Correct 23 ms 21972 KB Output is correct
14 Correct 17 ms 21972 KB Output is correct
15 Correct 22 ms 21972 KB Output is correct
16 Correct 18 ms 21972 KB Output is correct
17 Correct 22 ms 21972 KB Output is correct
18 Correct 17 ms 21972 KB Output is correct
19 Correct 17 ms 21972 KB Output is correct
20 Correct 17 ms 21972 KB Output is correct
21 Correct 18 ms 21972 KB Output is correct
22 Correct 18 ms 21972 KB Output is correct
23 Correct 20 ms 21972 KB Output is correct
24 Correct 18 ms 21972 KB Output is correct
25 Correct 18 ms 21972 KB Output is correct
26 Correct 17 ms 21972 KB Output is correct
27 Correct 18 ms 21972 KB Output is correct
28 Correct 21 ms 21972 KB Output is correct
29 Correct 17 ms 21972 KB Output is correct
30 Correct 18 ms 21972 KB Output is correct
31 Correct 18 ms 21972 KB Output is correct
32 Correct 17 ms 21972 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 18 ms 21972 KB Output is correct
2 Correct 18 ms 21972 KB Output is correct
3 Correct 18 ms 21972 KB Output is correct
4 Correct 18 ms 21972 KB Output is correct
5 Correct 18 ms 21972 KB Output is correct
6 Correct 19 ms 21972 KB Output is correct
7 Correct 18 ms 21972 KB Output is correct
8 Correct 18 ms 21972 KB Output is correct
9 Correct 18 ms 21972 KB Output is correct
10 Correct 18 ms 21972 KB Output is correct
11 Correct 22 ms 21972 KB Output is correct
12 Correct 21 ms 21972 KB Output is correct

Subtask #3
0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 29 ms 23292 KB Output is correct
2 Correct 36 ms 23292 KB Output is correct
3 Correct 35 ms 23324 KB Output is correct
4 Correct 28 ms 23324 KB Output is correct
5 Correct 27 ms 23324 KB Output is correct
6 Correct 26 ms 23324 KB Output is correct
7 Correct 27 ms 23324 KB Output is correct
8 Correct 23 ms 23324 KB Output is correct
9 Correct 26 ms 23324 KB Output is correct
10 Incorrect 22 ms 23324 KB Output isn't correct

Subtask #4
0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 232 ms 37732 KB Output is correct
2 Correct 238 ms 37732 KB Output is correct
3 Correct 296 ms 37796 KB Output is correct
4 Correct 277 ms 37796 KB Output is correct
5 Correct 171 ms 37796 KB Output is correct
6 Correct 157 ms 37796 KB Output is correct
7 Correct 212 ms 37796 KB Output is correct
8 Correct 43 ms 37796 KB Output is correct
9 Correct 81 ms 37796 KB Output is correct
10 Incorrect 107 ms 37796 KB Output isn't correct

Subtask #5
0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 820 ms 62572 KB Output is correct
2 Correct 830 ms 63696 KB Output is correct
3 Execution timed out 1008 ms 70964 KB Time limit exceeded
4 Halted 0 ms 0 KB -