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Submission #235385

# Submission time Handle Problem Language Result Execution time Memory
235385 2020-05-28T07:55:21 Z PeppaPig Palindromes (APIO14_palindrome) C++14
100 / 100
 998 ms 58232 KB 
#include <bits/stdc++.h>

#define long long long

using namespace std;

const int N = 6e5+5;

int n, sz;
int pos[N], sa[N], tmp[N], lcp[N][20];
char S[N];

void build_sa() {
    tmp[1] = 1;
    for(int i = 1; i <= sz; i++) sa[i] = i, pos[i] = S[i];
    for(int gap = 1; gap <= sz; gap <<= 1) {
        auto cmp = [&](int a, int b) {
            if(pos[a] != pos[b]) return pos[a] < pos[b];
            a += gap, b += gap;
            return (a <= sz && b <= sz) ? pos[a] < pos[b] : a > b;
        };
        sort(sa + 1, sa + 1 + sz, cmp);
        for(int i = 1; i < sz; i++) tmp[i + 1] = tmp[i] + cmp(sa[i], sa[i + 1]);
        for(int i = 1; i <= sz; i++) pos[sa[i]] = tmp[i];
    }

    for(int i = 1, k = 0; i <= sz; i++) if(pos[i] != sz) {
        for(int j = sa[pos[i] + 1]; S[i + k] == S[j + k]; k++);
        lcp[pos[i]][0] = k;
        if(k) --k;
    }
    for(int j = 0; j  < 19; j++) for(int i = 1; i <= sz; i++) {
        if(i + (1 << j) > sz) continue;
        lcp[i][j + 1] = min(lcp[i][j], lcp[i + (1 << j)][j]);
    }
}

int find_lcp(int l, int r) {
    if(l > r) swap(l, r);
    int k = 31 - __builtin_clz(r - l);
    return min(lcp[l][k], lcp[r - (1 << k)][k]);
}

int lp[N], cnt[N >> 1];
long ans;

void solve(int odd) {
    int len = 0;
    long sum; 
    for(int i = 1; i <= sz + 1; i++) {
        sum = 0;
        while(len > lcp[i - 1][0]) {
            sum += cnt[len], cnt[len] = 0;
            ans = max(ans, sum * (2 * len - odd));
            --len;
        }
        if(i == sz + 1) continue;
        cnt[len] += sum;
        len = max(len, lp[i]);
        ++cnt[lp[i]];
    }
}

int main() {
    scanf(" %s", S + 1);
    n = strlen(S + 1), sz = 2 * n + 1;
    S[n + 1] = '#';
    for(int i = 1; i <= n; i++) S[sz - i + 1] = S[i];
    build_sa();

    for(int i = 1; i <= n; i++) lp[pos[i]] = find_lcp(pos[i], pos[sz - i + 1]);
    solve(1);
    lp[pos[1]] = 0;
    for(int i = 2; i <= n; i++) lp[pos[i]] = find_lcp(pos[i], pos[sz - i + 2]);
    solve(0);
    
    printf("%lld\n", ans);

    return 0;
}

Compilation message

palindrome.cpp: In function 'int main()':
palindrome.cpp:65:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf(" %s", S + 1);
     ~~~~~^~~~~~~~~~~~~~

Subtask #1
8.0 / 8.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 384 KB Output is correct
2 Correct 4 ms 384 KB Output is correct
3 Correct 4 ms 384 KB Output is correct
4 Correct 4 ms 384 KB Output is correct
5 Correct 4 ms 384 KB Output is correct
6 Correct 5 ms 384 KB Output is correct
7 Correct 5 ms 384 KB Output is correct
8 Correct 4 ms 384 KB Output is correct
9 Correct 5 ms 384 KB Output is correct
10 Correct 4 ms 384 KB Output is correct
11 Correct 4 ms 384 KB Output is correct
12 Correct 5 ms 384 KB Output is correct
13 Correct 5 ms 384 KB Output is correct
14 Correct 5 ms 384 KB Output is correct
15 Correct 5 ms 384 KB Output is correct
16 Correct 5 ms 384 KB Output is correct
17 Correct 5 ms 384 KB Output is correct
18 Correct 4 ms 384 KB Output is correct
19 Correct 5 ms 384 KB Output is correct
20 Correct 4 ms 384 KB Output is correct
21 Correct 5 ms 384 KB Output is correct
22 Correct 5 ms 384 KB Output is correct
23 Correct 5 ms 384 KB Output is correct
24 Correct 4 ms 384 KB Output is correct
25 Correct 4 ms 384 KB Output is correct
26 Correct 4 ms 384 KB Output is correct
27 Correct 5 ms 384 KB Output is correct
28 Correct 5 ms 384 KB Output is correct
29 Correct 5 ms 384 KB Output is correct
30 Correct 5 ms 384 KB Output is correct
31 Correct 5 ms 384 KB Output is correct
32 Correct 5 ms 384 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 640 KB Output is correct
2 Correct 5 ms 512 KB Output is correct
3 Correct 5 ms 512 KB Output is correct
4 Correct 5 ms 512 KB Output is correct
5 Correct 5 ms 512 KB Output is correct
6 Correct 5 ms 512 KB Output is correct
7 Correct 6 ms 512 KB Output is correct
8 Correct 5 ms 512 KB Output is correct
9 Correct 5 ms 512 KB Output is correct
10 Correct 5 ms 512 KB Output is correct
11 Correct 5 ms 640 KB Output is correct
12 Correct 5 ms 512 KB Output is correct

Subtask #3
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 18 ms 2304 KB Output is correct
2 Correct 17 ms 2304 KB Output is correct
3 Correct 19 ms 2304 KB Output is correct
4 Correct 18 ms 2304 KB Output is correct
5 Correct 19 ms 2304 KB Output is correct
6 Correct 18 ms 2304 KB Output is correct
7 Correct 16 ms 2304 KB Output is correct
8 Correct 18 ms 2304 KB Output is correct
9 Correct 18 ms 2304 KB Output is correct
10 Correct 19 ms 2304 KB Output is correct

Subtask #4
26.0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 219 ms 19612 KB Output is correct
2 Correct 206 ms 19320 KB Output is correct
3 Correct 212 ms 19576 KB Output is correct
4 Correct 199 ms 19192 KB Output is correct
5 Correct 269 ms 19448 KB Output is correct
6 Correct 237 ms 19448 KB Output is correct
7 Correct 211 ms 19320 KB Output is correct
8 Correct 229 ms 19424 KB Output is correct
9 Correct 217 ms 19320 KB Output is correct
10 Correct 262 ms 19448 KB Output is correct

Subtask #5
27.0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 790 ms 57796 KB Output is correct
2 Correct 709 ms 57740 KB Output is correct
3 Correct 743 ms 58232 KB Output is correct
4 Correct 730 ms 57580 KB Output is correct
5 Correct 998 ms 58232 KB Output is correct
6 Correct 858 ms 57184 KB Output is correct
7 Correct 775 ms 57452 KB Output is correct
8 Correct 872 ms 57612 KB Output is correct
9 Correct 818 ms 57592 KB Output is correct
10 Correct 963 ms 58104 KB Output is correct
11 Correct 783 ms 58104 KB Output is correct
12 Correct 826 ms 57464 KB Output is correct