oj.uz

Submission #96694

# Submission time Handle Problem Language Result Execution time Memory
96694 2019-02-11T04:05:30 Z fjchf02 Palindromes (APIO14_palindrome) C++
100 / 100
 911 ms 30712 KB 
#include <bits/stdc++.h>

using namespace std;

const int N = 300010;

int n;
char s[N];
int a[N], gr[N], new_gr[N], ptr_gr[N], st[N], lcp[20][N];
int res[2 * N];
int l2[N];

bool cmp(int i, int j) {
  return s[i] < s[j];
}

void calc() {
  for (int i = 0; i < n; i++) {
    a[i] = i;
  }
  sort(a, a + n, cmp);
  gr[a[0]] = 0;
  for (int i = 1; i < n; i++) {
    gr[a[i]] = gr[a[i - 1]] + (s[a[i - 1]] != s[a[i]]);
  }
  int cnt = gr[a[n - 1]] + 1;
  int step = 1;
  while (cnt < n) {
    int ptr = 0;
    for (int i = n - step; i < n; i++) {
      st[ptr++] = i;
    }
    for (int i = 0; i < n; i++) {
      if (a[i] >= step) {
        st[ptr++] = a[i] - step;
      }
    }
    for (int i = n - 1; i >= 0; i--) {
      ptr_gr[gr[a[i]]] = i;
    }
    for (int i = 0; i < n; i++) {
      int x = st[i];
      a[ptr_gr[gr[x]]++] = x;
    }
    new_gr[a[0]] = 0;
    for (int i = 1; i < n; i++) {
      if (gr[a[i]] != gr[a[i - 1]]) {
        new_gr[a[i]] = new_gr[a[i - 1]] + 1;
      } else {
        int pre = (a[i - 1] + step < n ? gr[a[i - 1] + step] : -1);
        int cur = (a[i] + step < n ? gr[a[i] + step] : -1);
        new_gr[a[i]] = new_gr[a[i - 1]] + (pre != cur);
      }
    }
    copy(new_gr, new_gr + n, gr);
    cnt = gr[a[n - 1]] + 1;
    step <<= 1;
  }
  int k = 0;
  for (int i = 0; i < n; i++) {
    if (gr[i] == n - 1) {
      k = 0;  
    } else {
      k = max(0, k - 1);
      int j = a[gr[i] + 1];
      while (i + k < n && j + k < n && s[i + k] == s[j + k]) {
        k++;
      }
      lcp[0][gr[i]] = k;
    }
  }
  for (int k = 0; k < 19; k++) {
    int len = 1 << k;
    for (int i = 0; i + 2 * len - 1 < n - 1; i++) {
      lcp[k + 1][i] = min(lcp[k][i], lcp[k][i + len]);
    }
  }
}

int solve(int x, int len) {
  x = gr[x];
  int l = x, r = x - 1;
  {
    for (int i = l2[l + 1]; i >= 0; i--) {
      int nx = l - (1 << i);
      if (nx >= 0 && lcp[i][nx] >= len) {
        l = nx;
      }
    }
  }
  {
    for (int i = l2[n - x + 2]; i >= 0; i--) {
      int nx = r + (1 << i);
      if (nx < n - 1 && lcp[i][r + 1] >= len) {
        r = nx;
      }
    }
  }
  return r - l + 2;
}

int main() {
  for (int i = 2; i < N; i++) {
    l2[i] = l2[i >> 1] + 1;
  }
  scanf("%s", s);
  n = strlen(s);
  calc();
  int cnt[26];
  fill(cnt, cnt + 26, 0);
  for (int i = 0; i < n; i++) {
    cnt[int(s[i] - 'a')]++;
  }
  long long ans = *max_element(cnt, cnt + 26);
  int l = -1, r = -1;
  for (int z = 0; z < 2 * n - 1; z++) {
    int i = (z + 1) >> 1;
    int j = z >> 1;
    int& p = res[z];
    p = (i >= r ? 0 : min(r - i, res[2 * (l + r) - z]));
    int pre = res[2 * (l + r) - z];
    while (i - p - 1 >= 0 && j + p + 1 < n && s[i - p - 1] == s[j + p + 1]) {
      p++;
      if (p > pre) {
        int len = 2 * p + (z % 2 == 0);
        int last = i - p;
        ans = max(ans, (long long) len * solve(last, len));
      }
    }
    if (j + p > r) {
      l = i - p;
      r = j + p;
    }
  }
  printf("%lld\n", ans);
  return 0;
}

Compilation message

palindrome.cpp: In function 'int main()':
palindrome.cpp:106:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%s", s);
   ~~~~~^~~~~~~~~

Subtask #1
8.0 / 8.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 1528 KB Output is correct
2 Correct 3 ms 1528 KB Output is correct
3 Correct 3 ms 1528 KB Output is correct
4 Correct 3 ms 1528 KB Output is correct
5 Correct 3 ms 1528 KB Output is correct
6 Correct 3 ms 1528 KB Output is correct
7 Correct 3 ms 1528 KB Output is correct
8 Correct 3 ms 1532 KB Output is correct
9 Correct 3 ms 1612 KB Output is correct
10 Correct 3 ms 1532 KB Output is correct
11 Correct 3 ms 1528 KB Output is correct
12 Correct 3 ms 1528 KB Output is correct
13 Correct 3 ms 1528 KB Output is correct
14 Correct 2 ms 1528 KB Output is correct
15 Correct 3 ms 1528 KB Output is correct
16 Correct 3 ms 1528 KB Output is correct
17 Correct 3 ms 1528 KB Output is correct
18 Correct 3 ms 1528 KB Output is correct
19 Correct 3 ms 1656 KB Output is correct
20 Correct 3 ms 1528 KB Output is correct
21 Correct 3 ms 1656 KB Output is correct
22 Correct 3 ms 1700 KB Output is correct
23 Correct 3 ms 1528 KB Output is correct
24 Correct 3 ms 1656 KB Output is correct
25 Correct 3 ms 1528 KB Output is correct
26 Correct 3 ms 1528 KB Output is correct
27 Correct 3 ms 1528 KB Output is correct
28 Correct 3 ms 1528 KB Output is correct
29 Correct 3 ms 1528 KB Output is correct
30 Correct 3 ms 1628 KB Output is correct
31 Correct 3 ms 1656 KB Output is correct
32 Correct 3 ms 1656 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 1656 KB Output is correct
2 Correct 3 ms 1656 KB Output is correct
3 Correct 3 ms 1660 KB Output is correct
4 Correct 3 ms 1656 KB Output is correct
5 Correct 4 ms 1656 KB Output is correct
6 Correct 3 ms 1656 KB Output is correct
7 Correct 3 ms 1656 KB Output is correct
8 Correct 4 ms 1656 KB Output is correct
9 Correct 3 ms 1656 KB Output is correct
10 Correct 4 ms 1656 KB Output is correct
11 Correct 3 ms 1656 KB Output is correct
12 Correct 4 ms 1656 KB Output is correct

Subtask #3
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 2424 KB Output is correct
2 Correct 5 ms 2424 KB Output is correct
3 Correct 5 ms 2424 KB Output is correct
4 Correct 5 ms 2424 KB Output is correct
5 Correct 8 ms 2424 KB Output is correct
6 Correct 7 ms 2424 KB Output is correct
7 Correct 5 ms 2424 KB Output is correct
8 Correct 5 ms 2424 KB Output is correct
9 Correct 5 ms 2424 KB Output is correct
10 Correct 9 ms 2428 KB Output is correct

Subtask #4
26.0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 37 ms 10460 KB Output is correct
2 Correct 40 ms 10488 KB Output is correct
3 Correct 34 ms 10488 KB Output is correct
4 Correct 36 ms 10488 KB Output is correct
5 Correct 106 ms 10536 KB Output is correct
6 Correct 69 ms 10616 KB Output is correct
7 Correct 52 ms 10528 KB Output is correct
8 Correct 29 ms 10500 KB Output is correct
9 Correct 53 ms 10584 KB Output is correct
10 Correct 92 ms 10744 KB Output is correct

Subtask #5
27.0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 124 ms 30172 KB Output is correct
2 Correct 129 ms 30172 KB Output is correct
3 Correct 108 ms 30200 KB Output is correct
4 Correct 110 ms 30044 KB Output is correct
5 Correct 911 ms 30108 KB Output is correct
6 Correct 177 ms 30712 KB Output is correct
7 Correct 209 ms 30584 KB Output is correct
8 Correct 98 ms 30288 KB Output is correct
9 Correct 98 ms 30304 KB Output is correct
10 Correct 819 ms 30584 KB Output is correct
11 Correct 148 ms 30508 KB Output is correct
12 Correct 191 ms 30584 KB Output is correct