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Submission #253817

# Submission time Handle Problem Language Result Execution time Memory
253817 2020-07-28T18:28:55 Z Bruteforceman Lampice (COCI19_lampice) C++11
42 / 110
 5000 ms 13192 KB 
#include <bits/stdc++.h>
using namespace std;
const int maxn = 5e4 + 5;
const int mod = 1e9 + 7;
const int base = 131;
vector <int> g[maxn];
long long power[maxn], up[maxn], down[maxn];
int sub[maxn], dep[maxn];
bool vis[maxn];
char s[maxn];
 
void subtree(int x, int par) {
  sub[x] = 1;
  for(int i : g[x]) {
    if(vis[i]) continue;
    if(i != par) {
      subtree(i, x);
      sub[x] += sub[i];
    }
  }
}
int centroid(int x, int par, int range) {
  for(int i : g[x]) {
    if(vis[i]) continue;
    if(i != par && sub[i] > range) {
      return centroid(i, x, range);
    }
  }
  return x;
}
void dfs(int x, int par) {
  for(int i : g[x]) {
    if(vis[i]) continue;
    if(i != par) {
      dep[i] = 1 + dep[x];
      down[i] = (down[x] * base + s[i]) % mod;
      up[i] = (power[dep[i]] * s[i] + up[x]) % mod;
      dfs(i, x);
    }
  }
}
void getNode(int x, int par, vector <int> &node) {
  node.push_back(x);
  for(auto i : g[x]) {
    if(!vis[i] && i != par) {
      getNode(i, x, node);
    }
  }
}
set <int> table[maxn];
bool solve(int x, int k) {
  subtree(x, 0);
  x = centroid(x, 0, sub[x] / 2);
  dep[x] = 0;
  up[x] = down[x] = s[x];
  dfs(x, 0);
  bool ans = false;
  for(int i : g[x]) {
    if(vis[i]) continue;
    vector <int> node;
    vector <pair <int, int>> cont;
    getNode(i, x, node);
    for(auto j : node) {
      if(dep[j] + 1 == k) {
        ans |= (down[j] == up[j]);    
      } else if (dep[j] < k) {
        long long value = (up[j] * power[k - dep[j] - 1] - down[j] + power[dep[j]] * s[x] + mod) % mod;
        ans |= table[k - dep[j] - 1].find(value) != table[k - dep[j] - 1].end();
        cont.emplace_back(dep[j], value);
      }
    }
    for(auto j : cont) table[j.first].insert(j.second);
  }
  vector <int> node;
  getNode(x, 0, node);
  for(auto i : node) {
    table[dep[i]].clear();
  }
  vis[x] = true;
  for(int i : g[x]) {
    if(vis[i]) continue;
    ans |= solve(i, k);
  }
  return ans;
}
 
int main() {
  int n;
  scanf("%d", &n);
  scanf("%s", s + 1);
  power[0] = 1;
  for(int i = 1; i <= n; i++) {
    power[i] = (power[i - 1] * base) % mod;
  }
  for(int i = 1; i < n; i++) {
    int p, q;
    scanf("%d %d", &p, &q);
    g[p].push_back(q);
    g[q].push_back(p);
  }
  
 
 
 
  int ans;
  int l = 1, r = (n + 1) / 2;
  while(l < r) {
    int mid = (l + r + 1) >> 1;
    memset(vis, false, sizeof vis);
    if(solve(1, 2 * mid - 1)) {
      l = mid;
    } else {
      r = mid - 1;
    }
  }
  ans = 2 * l - 1;
  l = 0; r = (n / 2);
  while(l < r) {
    int mid = (l + r + 1) >> 1;
    memset(vis, false, sizeof vis);
    if(solve(1, mid * 2)) {
      l = mid;
    } else {
      r = mid - 1;
    }
  }
  ans = max(ans, l * 2);
  printf("%d\n", ans);
  return 0;
}

Compilation message

lampice.cpp: In function 'int main()':
lampice.cpp:89:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &n);
   ~~~~~^~~~~~~~~~
lampice.cpp:90:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%s", s + 1);
   ~~~~~^~~~~~~~~~~~~
lampice.cpp:97:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d", &p, &q);
     ~~~~~^~~~~~~~~~~~~~~~~

Subtask #1
17.0 / 17.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 3968 KB Output is correct
2 Correct 18 ms 3968 KB Output is correct
3 Correct 54 ms 4136 KB Output is correct
4 Correct 73 ms 4096 KB Output is correct
5 Correct 3 ms 3840 KB Output is correct
6 Correct 3 ms 3968 KB Output is correct
7 Correct 2 ms 3968 KB Output is correct

Subtask #2
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 2272 ms 11760 KB Output is correct
2 Correct 2697 ms 11916 KB Output is correct
3 Correct 2984 ms 12144 KB Output is correct
4 Correct 2945 ms 12972 KB Output is correct
5 Correct 3109 ms 13192 KB Output is correct
6 Correct 2577 ms 11952 KB Output is correct

Subtask #3
0 / 31.0

# Verdict Execution time Memory Grader output
1 Correct 4607 ms 10736 KB Output is correct
2 Execution timed out 5081 ms 10408 KB Time limit exceeded
3 Halted 0 ms 0 KB -

Subtask #4
0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 3968 KB Output is correct
2 Correct 18 ms 3968 KB Output is correct
3 Correct 54 ms 4136 KB Output is correct
4 Correct 73 ms 4096 KB Output is correct
5 Correct 3 ms 3840 KB Output is correct
6 Correct 3 ms 3968 KB Output is correct
7 Correct 2 ms 3968 KB Output is correct
8 Correct 2272 ms 11760 KB Output is correct
9 Correct 2697 ms 11916 KB Output is correct
10 Correct 2984 ms 12144 KB Output is correct
11 Correct 2945 ms 12972 KB Output is correct
12 Correct 3109 ms 13192 KB Output is correct
13 Correct 2577 ms 11952 KB Output is correct
14 Correct 4607 ms 10736 KB Output is correct
15 Execution timed out 5081 ms 10408 KB Time limit exceeded
16 Halted 0 ms 0 KB -