#include <bits/stdc++.h>
#define ll long long
#define FOR(i,a,b) for (int i = (a), _b = (b); i <= _b; i++)
#define FOD(i,b,a) for (int i = (b), _a = (a); i >= _a; i--)
#define FORE(i, v) for (__typeof((v).begin()) i = (v).begin(); i != (v).end(); i++)
#define ALL(v) (v).begin(), (v).end()
#define BIT(x, i) (((x) >> (i)) & 1)
#define MASK(i) (1LL << (i))
#define CNTBIT(x) __builtin_popcount(x)
#define fi first
#define se second
#define pb push_back
#define eb emplace_back
#define left ___left
#define right ___right
#define pii pair<int, int>
#define DEBUG(n, a) FOR (i, 1, n) cout << a[i] << ' '; cout << endl;1234567890
#define lob lower_bound // >=
#define upb upper_bound // >
#define endl "\n"
using namespace std;
template<class X, class Y> bool maximize(X &x, Y y){ if (x < y){ x = y; return true; } return false; }
template<class X, class Y> bool minimize(X &x, Y y){ if (x > y){ x = y; return true; } return false; }
#define gogobruhbruh ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
#define file(name) if (fopen (name".inp", "r")) { freopen (name".inp", "r", stdin); freopen (name".out", "w", stdout); }
int MOD = 1e9 + 7;
void add(int &a, int b){ if ((a += b) >= MOD) a -= MOD; }
int sub(int a, int b){ if ((a -= b) < 0) a += MOD; return a; }
int muti(int a, int b){ return (1LL * a * b) % MOD; }
int Pow(int x, int y){ int res = 1; for (; y; y >>= 1){ if (y & 1) res = muti(res, x); x = muti(x, x); } return res; }
const int MAX = 5e4 + 7;
const int INF = 1e9 + 7;
const int BASE = 311;
int num, res = 1, mx;
int val[MAX], sz[MAX], pw[MAX];
vector<unordered_set<int>> dp;
vector<int> edge[MAX];
vector<pii> V;
bool del[MAX];
void dfs(int u, int pre){
sz[u] = 1;
// if (pre)
// cout << pre << '-' << char(val[pre]) << ' ' << u << '-' << char(val[u]) << endl;
for (int v : edge[u])
if (!del[v] && v != pre){
// if (u == 25987){
// cout << v << ' ' << edge[v].size() << endl;
// return;
// }
dfs(v, u),
sz[u] += sz[v];
}
}
int centroid(int u, int pre, int n){
for (int v : edge[u])
if (!del[v] && v != pre && sz[v] > n)
return centroid(v, u, n);
return u;
}
bool dfs2(int u, int pre, int dep, int up, int down, int target){
if (dep > target)
return 0;
add(up, muti(val[u], pw[dep - 1]));
if (pre)
down = muti(down, BASE), add(down, val[u]);
int code = sub(muti(up, pw[target - dep]), down);
if (dp[target - dep].find(code) != dp[target - dep].end())
return 1;
for (int v : edge[u])
if (!del[v] && v != pre){
if (dfs2(v, u, dep + 1, up, down, target))
return 1;
if (pre)
continue;
for (auto[dep, code] : V)
dp[dep].insert(code);
V.clear();
}
maximize(mx, dep);
V.pb({dep - 1, code});
return 0;
}
bool calc(int u, int target){
dfs(u, -1);
u = centroid(u, -1, sz[u] >> 1);
mx = 0;
dp[0].insert(muti(val[u], pw[target - 1]));
if (dfs2(u, 0, 1, 0, 0, target))
return 1;
FOR (i, 1, mx)
dp[i].clear();
del[u] = 1;
for (int v : edge[u])
if (!del[v])
if (calc(v, target))
return 1;
return 0;
}
bool check(int len){
FOR (i, 1, num)
del[i] = 0;
return calc(1, len);
}
void solve(){
dp.resize(num + 1);
pw[0] = 1;
FOR (i, 1, num)
pw[i] = muti(pw[i - 1], BASE);
int left = 0, right = num >> 1, res = 1;
while (left <= right){
int mid = (left + right) / 2;
if (check(mid << 1)){
res = mid << 1;
left = mid + 1;
}else
right = mid - 1;
}
left = 0, right = (num - 1) >> 1;
while (left <= right){
int mid = (left + right) >> 1;
if (check(mid << 1 | 1)){
maximize(res, mid << 1 | 1);
left = mid + 1;
}else
right = mid - 1;
}
cout << res;
}
void read(){
string s;
cin >> num >> s;
FOR (i, 1, num)
val[i] = s[i - 1];
FOR (i, 2, num){
static int u, v;
cin >> u >> v;
edge[u].eb(v);
edge[v].eb(u);
}
}
int main(){
gogobruhbruh;
file("main");
int test = 1;
// cin >> test;
while (test--)
read(),
solve();
}
Compilation message
lampice.cpp: In function 'int main()':
lampice.cpp:28:61: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
28 | #define file(name) if (fopen (name".inp", "r")) { freopen (name".inp", "r", stdin); freopen (name".out", "w", stdout); }
| ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
lampice.cpp:158:5: note: in expansion of macro 'file'
158 | file("main");
| ^~~~
lampice.cpp:28:95: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
28 | #define file(name) if (fopen (name".inp", "r")) { freopen (name".inp", "r", stdin); freopen (name".out", "w", stdout); }
| ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
lampice.cpp:158:5: note: in expansion of macro 'file'
158 | file("main");
| ^~~~
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
3 ms |
1492 KB |
Output is correct |
| 2 |
Correct |
7 ms |
1620 KB |
Output is correct |
| 3 |
Correct |
17 ms |
1780 KB |
Output is correct |
| 4 |
Correct |
19 ms |
1812 KB |
Output is correct |
| 5 |
Correct |
1 ms |
1492 KB |
Output is correct |
| 6 |
Incorrect |
1 ms |
1504 KB |
Output isn't correct |
| 7 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
842 ms |
13248 KB |
Output is correct |
| 2 |
Correct |
860 ms |
15136 KB |
Output is correct |
| 3 |
Correct |
552 ms |
21776 KB |
Output is correct |
| 4 |
Correct |
707 ms |
21912 KB |
Output is correct |
| 5 |
Correct |
1099 ms |
16664 KB |
Output is correct |
| 6 |
Correct |
213 ms |
38892 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
1446 ms |
10444 KB |
Output is correct |
| 2 |
Correct |
1641 ms |
10036 KB |
Output is correct |
| 3 |
Correct |
1477 ms |
10660 KB |
Output is correct |
| 4 |
Correct |
1355 ms |
11120 KB |
Output is correct |
| 5 |
Correct |
1064 ms |
13708 KB |
Output is correct |
| 6 |
Correct |
1164 ms |
8820 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
3 ms |
1492 KB |
Output is correct |
| 2 |
Correct |
7 ms |
1620 KB |
Output is correct |
| 3 |
Correct |
17 ms |
1780 KB |
Output is correct |
| 4 |
Correct |
19 ms |
1812 KB |
Output is correct |
| 5 |
Correct |
1 ms |
1492 KB |
Output is correct |
| 6 |
Incorrect |
1 ms |
1504 KB |
Output isn't correct |
| 7 |
Halted |
0 ms |
0 KB |
- |
