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Submission #848932

# Submission time Handle Problem Language Result Execution time Memory
848932 2023-09-13T18:05:57 Z qthang2k11 Lampice (COCI19_lampice) C++17
110 / 110
 2439 ms 11700 KB 
#include <bits/stdc++.h>
using namespace std;

using ll = long long;

const int N = 5e4 + 5, mod = 1e9 + 7, base = 31;
unordered_set<int> mp, existed;
int xuoi[N], nguoc[N], pw[N];
int dpt[N], up[N], sz[N];
bool rem[N], checked;
vector <int> adj[N];
int ans = 1, n, r;
char a[N];

int add(int value, char x) {
   return (value * base + x - 'a' + 1);
}

int dfs(int x, int p) {
   sz[x] = 1;
   for (int y: adj[x]) {
      if (y == p || rem[y]) continue;
      sz[x] += dfs(y, x);
   }

   return sz[x];
}

void down(int x, int p, int len) {
   dpt[x] = dpt[p] + 1;
   up[dpt[x]] = x;
   if (dpt[x] >= len || checked) return;
   int curlen = dpt[x] + 1;
   if (curlen == len) {
      ///centroid->con
      ///xuoi == nguoc
      int Xuoi = xuoi[x] + (a[r] - 'a' + 1) * pw[dpt[x]];
      int Nguoc = nguoc[x] * base + (a[r] - 'a' + 1);
      if (Xuoi == Nguoc) return checked = 1, void();
   }
   mp.insert(xuoi[x]);
   for (int y: adj[x]) {
      if (y == p || rem[y]) continue;
      xuoi[y] = add(xuoi[x], a[y]);
      nguoc[y] = nguoc[x] + (a[y] - 'a' + 1) * pw[dpt[x]];
      down(y, x, len);
   }
   if (checked) return;
   if (curlen >= (len + 1) / 2) {
      int xx = len - curlen;
      if (xx <= curlen) {
         ///curstr[curlen-1,...,curlen-x]..curstr
         if (xx > dpt[x]) return;
         int chaxet = up[dpt[x] - xx]; //jump(x,xx);///log
         int Xuoi = xuoi[chaxet] + (a[r] - 'a' + 1) * pw[dpt[chaxet]];
         int Nguoc = nguoc[chaxet] * base + (a[r] - 'a' + 1);
         if (Xuoi != Nguoc) return;
         int suffix = xuoi[x] - xuoi[chaxet] * pw[xx];
         if (existed.find(suffix) != existed.end())
            return checked = 1, void();
      }
   }
}

bool ok(int x, int len) {
   if (sz[x] < len) return 0;
   if (len <= 1) return 1;
   dpt[x] = 0;
   xuoi[x] = nguoc[x] = 0;
   r = x;
   existed.clear();
   checked = 0;
   for (int y: adj[x]) {
      if (rem[y]) continue;
      mp.clear();
      xuoi[y] = nguoc[y] = a[y] - 'a' + 1;
      down(y, x, len);
      for (int x: mp)
         existed.insert(x);
   }
   return checked;
}

void sus(int x, int p) {
   sz[x] = 1;
   for (int y: adj[x]) {
      if (y == p || rem[y]) continue;
      sus(y, x);
      sz[x] += sz[y];
   }
}

void solve(int x) {
   {
      ///chan
      int l = ans / 2, r = sz[x];
      while (l <= r) {
         int mid = (l + r) / 2;
         if (ok(x, mid * 2)) {
            ans = max(ans, mid * 2);
            l = mid + 1;
         } else r = mid - 1;
      }
   }
   {
      ///le
      int l = ans / 2, r = sz[x];
      while (l <= r) {
         int mid = (l + r) / 2;
         if (ok(x, mid * 2 + 1)) {
            ans = max(ans, mid * 2 + 1);
            l = mid + 1;
         } else r = mid - 1;
      }
   }
   reverse(adj[x].begin(), adj[x].end());
}

int find_centroid(int x, int p, int tot) {
   for (int y: adj[x])
      if (y != p && !rem[y] && sz[y] > tot / 2)
         return find_centroid(y, x, tot);
   return x;
}

void build(int x = 1) {
   int c = find_centroid(x, 0, dfs(x, 0));
   rem[c] = 1;
   sus(c, 0);
   solve(c);
   solve(c);
   for (int y: adj[c])
      if (!rem[y])
         build(y);
}

int32_t main() {
   cin.tie(0)->sync_with_stdio(0);
   cin >> n;
   pw[0] = 1;
   for (int i = 1; i <= n; i++) pw[i] = 1ll * pw[i - 1] * base;
   for (int i = 1; i <= n; i++) cin >> a[i];
   for (int i = 1; i < n; i++) {
      int x, y;
      cin >> x >> y;
      adj[x].push_back(y);
      adj[y].push_back(x);
   }
   build();
   cout << ans;
   return 0;
}

Subtask #1
17.0 / 17.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2648 KB Output is correct
2 Correct 4 ms 2652 KB Output is correct
3 Correct 13 ms 2652 KB Output is correct
4 Correct 10 ms 2808 KB Output is correct
5 Correct 1 ms 2396 KB Output is correct
6 Correct 1 ms 2652 KB Output is correct
7 Correct 1 ms 2652 KB Output is correct

Subtask #2
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 1201 ms 10680 KB Output is correct
2 Correct 540 ms 10940 KB Output is correct
3 Correct 161 ms 10932 KB Output is correct
4 Correct 166 ms 11204 KB Output is correct
5 Correct 396 ms 11700 KB Output is correct
6 Correct 37 ms 10420 KB Output is correct

Subtask #3
31.0 / 31.0

# Verdict Execution time Memory Grader output
1 Correct 1500 ms 8624 KB Output is correct
2 Correct 846 ms 8348 KB Output is correct
3 Correct 810 ms 8632 KB Output is correct
4 Correct 491 ms 7540 KB Output is correct
5 Correct 593 ms 7852 KB Output is correct
6 Correct 688 ms 7084 KB Output is correct

Subtask #4
37.0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2648 KB Output is correct
2 Correct 4 ms 2652 KB Output is correct
3 Correct 13 ms 2652 KB Output is correct
4 Correct 10 ms 2808 KB Output is correct
5 Correct 1 ms 2396 KB Output is correct
6 Correct 1 ms 2652 KB Output is correct
7 Correct 1 ms 2652 KB Output is correct
8 Correct 1201 ms 10680 KB Output is correct
9 Correct 540 ms 10940 KB Output is correct
10 Correct 161 ms 10932 KB Output is correct
11 Correct 166 ms 11204 KB Output is correct
12 Correct 396 ms 11700 KB Output is correct
13 Correct 37 ms 10420 KB Output is correct
14 Correct 1500 ms 8624 KB Output is correct
15 Correct 846 ms 8348 KB Output is correct
16 Correct 810 ms 8632 KB Output is correct
17 Correct 491 ms 7540 KB Output is correct
18 Correct 593 ms 7852 KB Output is correct
19 Correct 688 ms 7084 KB Output is correct
20 Correct 848 ms 5976 KB Output is correct
21 Correct 1345 ms 6988 KB Output is correct
22 Correct 1311 ms 8276 KB Output is correct
23 Correct 383 ms 5316 KB Output is correct
24 Correct 476 ms 6492 KB Output is correct
25 Correct 457 ms 6108 KB Output is correct
26 Correct 1040 ms 8108 KB Output is correct
27 Correct 2439 ms 8376 KB Output is correct
28 Correct 534 ms 5220 KB Output is correct
29 Correct 569 ms 5208 KB Output is correct
30 Correct 520 ms 7004 KB Output is correct
31 Correct 591 ms 5724 KB Output is correct
32 Correct 334 ms 8280 KB Output is correct
33 Correct 796 ms 7192 KB Output is correct