oj.uz

답안 #635855

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
635855 2022-08-27T08:11:22 Z HaYoungJoon Lampice (COCI19_lampice) C++17
73 / 110
 3209 ms 21608 KB 
#include <bits/stdc++.h>
#define ll long long

using namespace std;

typedef pair<int,int> pii;
const int maxn = 5e4 + 1;
const int LOG = 16;
const int base = 31;
const int modu = 1e9 + 7;
int n, pos[maxn], name[2*maxn], numNode, res = 0, timer1 = 0, timer = 0, RMQ[LOG+1][2*maxn], H[maxn], Lg[2*maxn]; ///LCA
char color[maxn];
int child[maxn], root = -1, node[maxn], sta[maxn], fin[maxn];
bool vis[maxn];            ///Centroid
int hashT[maxn], hashN[maxn], POW[maxn], inv_POW[maxn]; ///Hash
vector<int> adj[maxn], adjC[maxn];

#define MIN_HIGH(x,y) (H[name[x]] < H[name[y]] ? (x) : (y))

struct hashFunction
{
  size_t operator()(const pair<int ,
                    int> &x) const
  {
    return x.first ^ x.second;
  }
};

int add(int A, int B) {
    ll tmp = A+B;
    if (tmp >= modu) tmp -= modu;
    if (tmp < 0) tmp += modu;
    return tmp;
}
int mul(int A, int B) {
    ll tmp = 1LL*A*B;
    if (tmp >= modu) tmp %= modu;
    return tmp;
}

void DFS_init(int u, int p) {
    pos[u] = ++timer1;
    name[timer1] = u;
    for (int v: adj[u]) {
        if (v == p) continue;
        H[v] = H[u] + 1;
        hashT[v] = add(color[v], mul(hashT[u],POW[1]));
        hashN[v] = add(mul(color[v],POW[H[v]]),hashN[u]);
        DFS_init(v,u);
        name[++timer1] = u;
    }
}

int LCA(int u, int v) {
    int l = pos[u], r = pos[v];
    if (l > r) swap(l,r);
    int k = Lg[r-l+1];
    return name[MIN_HIGH(RMQ[k][l],RMQ[k][r - (1 << k) + 1])];
}

int binexpo(ll A, int b) {
    int res = 1;
    while (b) {
        if (b & 1) res = 1LL*res*A%modu;
        A = A*A % modu;
        b >>= 1;
    }
    return res;
}
int inv(int A) {
    return binexpo(A,modu-2);
}

int getHash(int u, int v, bool type) {
    int L = LCA(u,v);
    int hash_u = add(add(hashT[u], -mul(hashT[L],POW[H[u] - H[L]] )),mul(color[L],POW[H[u] - H[L]])), hash_v = add(hashN[v],-hashN[L]);
    int target = H[u] - H[L];
    if (H[L] <= target) hash_v = mul(hash_v,POW[target - H[L]]);
    else hash_v = mul(hash_v,inv_POW[H[L] - target]);
    if (type) hash_v = add(hash_v,-mul(color[v],POW[H[u] + H[v] - 2*H[L]]));
    return add(hash_u,hash_v);
}

void DFS_size(int u, int p) {
    child[u] = 1;
    for (int v: adj[u]) {
        if (v == p || vis[v]) continue;
        DFS_size(v,u);
        child[u] += child[v];
    }
}

int get_centroid(int u, int p, int _n) {
    for (int v: adj[u]) {
        if (v == p || vis[v]) continue;
        if (child[v] > _n/2) return get_centroid(v,u,_n);
    }
    return u;
}

void centroid_init(int u, int p) {
    DFS_size(u,u);
    int c = get_centroid(u,u,child[u]);
    vis[c] = 1;
    if (p != -1) adjC[p].push_back(c);
    if (root == -1) root = c;
    for (int v: adj[c]) {
        if (vis[v]) continue;
        centroid_init(v,c);
    }
}

void DFS_centroid(int u) {
    sta[u] = ++timer;
    node[sta[u]] = u;
    for (int v: adjC[u]) {
        DFS_centroid(v);
    }
    fin[u] = timer;
}

void init() {
    POW[0] = 1;
    inv_POW[0] = 1;
    for (int i = 1; i <= n; i++) {
        POW[i] = mul(POW[i-1],base);
        inv_POW[i] = inv(POW[i]);
    }
    hashT[1] = hashN[1] = color[1];
    DFS_init(1,-1);
    for (int i = 1; i <= timer1; i++) RMQ[0][i] = i;
    for (int j = 1; j <= LOG; j++)
        for (int i = 1; i <= timer1 - (1 << j)+1;i++)
        RMQ[j][i] = MIN_HIGH(RMQ[j-1][i],RMQ[j-1][i + (1 << (j-1))]);
    centroid_init(1,-1);
    DFS_centroid(root);
}

bool curAns;

void DFS_ans(int u) {
    vector<pii> tmp;
    unordered_set<pii,hashFunction> st;
    for (int v: adjC[u]) {
        for (int i = sta[v]; i <= fin[v]; i++) {
            int d = H[u] + H[node[i]] - 2*H[LCA(u,node[i])] + 1;
            if (d == numNode) {
                if (getHash(node[i],u,0) == getHash(u,node[i],0)) {
                    curAns = 1;
                    return;
                }
            } else if (d < numNode) {
                int need = add(getHash(node[i],u,1),-mul(getHash(u,node[i],0),POW[numNode - d]));
                if (st.find(pii(numNode - d + 1,need)) != st.end()) {
                    curAns = 1;
                    return;
                }
                tmp.emplace_back(pii(d,need));
            }
        }
        if (v != adj[u].back())
            for (int i = 0; i < tmp.size(); i++) st.insert(tmp[i]);
        tmp.clear();
    }
    st.clear();
    for (int v: adjC[u]) {
        DFS_ans(v);
        if (curAns) return;
    }
}

bool getAns() {
    curAns = 0;
    DFS_ans(root);
    return curAns;
}

int main()
{
    ios_base::sync_with_stdio(0); cin.tie(0);
    cin >> n;
    Lg[0] = -1;
    for (int i = 1; i <= 2*n; i++) Lg[i] = Lg[i/2] + 1;
    for (int i = 1; i <= n; i++) {
        char c;
        cin >> c;
        color[i] = c - 'a';
    }
    for (int i = 1; i < n; i++) {
        int u,v;
        cin >> u >> v;
        adj[u].emplace_back(v);
        adj[v].emplace_back(u);
    }
    init();
    int L = 1, R = n/2, res = 1;
    while (L <= R) {
        int mid = (L + R)/2;
        numNode = 2*mid;
        if (getAns()) {
            res =max(res,2*mid);
            L = mid+1;
        } else R = mid-1;
    }
    L = res/2; R = (n-1)/2;
    while (L <= R) {
        int mid = (L + R)/2;
        numNode = 2*mid + 1;
        if (getAns()) {
            res = max(res,2*mid+1);
            L = mid+1;
        } else R = mid-1;
    }
    cout << res;
    return 0;
}

Compilation message

lampice.cpp: In function 'void DFS_ans(int)':
lampice.cpp:162:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  162 |             for (int i = 0; i < tmp.size(); i++) st.insert(tmp[i]);
      |                             ~~^~~~~~~~~~~~

Subtask #1
17.0 / 17.0

# 결과 실행 시간 메모리 Grader output
1 Correct 5 ms 2772 KB Output is correct
2 Correct 11 ms 2964 KB Output is correct
3 Correct 35 ms 3080 KB Output is correct
4 Correct 36 ms 3284 KB Output is correct
5 Correct 2 ms 2644 KB Output is correct
6 Correct 2 ms 2644 KB Output is correct
7 Correct 2 ms 2676 KB Output is correct

Subtask #2
25.0 / 25.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1852 ms 19256 KB Output is correct
2 Correct 1955 ms 19720 KB Output is correct
3 Correct 605 ms 20108 KB Output is correct
4 Correct 886 ms 20716 KB Output is correct
5 Correct 2932 ms 21608 KB Output is correct
6 Correct 106 ms 20168 KB Output is correct

Subtask #3
31.0 / 31.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2318 ms 18224 KB Output is correct
2 Correct 3209 ms 17864 KB Output is correct
3 Correct 2833 ms 17828 KB Output is correct
4 Correct 1947 ms 17164 KB Output is correct
5 Correct 1921 ms 16592 KB Output is correct
6 Correct 1878 ms 14848 KB Output is correct

Subtask #4
0 / 37.0

# 결과 실행 시간 메모리 Grader output
1 Correct 5 ms 2772 KB Output is correct
2 Correct 11 ms 2964 KB Output is correct
3 Correct 35 ms 3080 KB Output is correct
4 Correct 36 ms 3284 KB Output is correct
5 Correct 2 ms 2644 KB Output is correct
6 Correct 2 ms 2644 KB Output is correct
7 Correct 2 ms 2676 KB Output is correct
8 Correct 1852 ms 19256 KB Output is correct
9 Correct 1955 ms 19720 KB Output is correct
10 Correct 605 ms 20108 KB Output is correct
11 Correct 886 ms 20716 KB Output is correct
12 Correct 2932 ms 21608 KB Output is correct
13 Correct 106 ms 20168 KB Output is correct
14 Correct 2318 ms 18224 KB Output is correct
15 Correct 3209 ms 17864 KB Output is correct
16 Correct 2833 ms 17828 KB Output is correct
17 Correct 1947 ms 17164 KB Output is correct
18 Correct 1921 ms 16592 KB Output is correct
19 Correct 1878 ms 14848 KB Output is correct
20 Correct 1647 ms 14464 KB Output is correct
21 Correct 1987 ms 15296 KB Output is correct
22 Correct 2521 ms 16368 KB Output is correct
23 Correct 663 ms 13840 KB Output is correct
24 Correct 2410 ms 16060 KB Output is correct
25 Correct 1683 ms 15696 KB Output is correct
26 Correct 2557 ms 17412 KB Output is correct
27 Incorrect 2499 ms 17392 KB Output isn't correct
28 Halted 0 ms 0 KB -