oj.uz

답안 #342378

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
342378 2021-01-02T02:49:06 Z limabeans Papričice (COCI20_papricice) C++17
110 / 110
 897 ms 47712 KB 
#include <bits/stdc++.h>
using namespace std;

template<typename T>
void out(T x) { cout << x << endl; exit(0); }
#define watch(x) cout << (#x) << " is " << (x) << endl







const int maxn = 2e5 + 10;
const int LOG = 20;

int n;
vector<int> g[maxn];
int par[LOG+1][maxn];
int dep[maxn];
int siz[maxn];

void hack(int at, int p=0) {
    for (int i=1; i<LOG; i++) {
	par[i][at] = par[i-1][par[i-1][at]];
    }

    siz[at] = 1;
    
    for (int to: g[at]) {
	if (to==p) continue;
	dep[to]=1+dep[at];
	par[0][to]=at;
	hack(to, at);
	siz[at] += siz[to];
    }
}


int lca(int u, int v) {
    if (dep[u] < dep[v]) swap(u,v);
    int dx = dep[u]-dep[v];
    for (int i=0; i<LOG; i++) {
	if (dx>>i&1) {
	    u = par[i][u];
	}
    }
    if (u==v) return u;

    for (int j=LOG-1; j>=0; j--) {
	if (par[j][u]!=par[j][v]) {
	    u = par[j][u];
	    v = par[j][v];
	}
    }

    return par[0][u];
}

int get(vector<int> a) {
    sort(a.begin(),a.end());
    return a[2]-a[0];
}

int lo;


vector<int> vfind(multiset<int> &s, int x) {
    if (s.empty()) return {};
    
    auto iter = s.lower_bound(x);
    if (iter == s.end()) --iter;


    vector<int> res;
    res.push_back(*iter);
    auto piter = iter;
    
    //fwd
    for (int it=0; it<2; it++) {
	++iter;
	if (iter==s.end()) break;
	res.push_back(*iter);	
    }

    iter = piter;
    //prv
    for (int it=0; it<2; it++) {
	if (iter==s.begin()) break;
	--iter;
	res.push_back(*iter);	
    }
    
    return res;
}

multiset<int> A, B;

vector<int> solveA(int x) {
    vector<int> res;
    
    auto tmp = vfind(A, (n+x)/2);
    res.insert(res.end(), tmp.begin(), tmp.end());

    tmp = vfind(A, n-x);
    res.insert(res.end(), tmp.begin(), tmp.end());

    tmp = vfind(A, 2*x);
    res.insert(res.end(), tmp.begin(), tmp.end());
    
    return res;
}

vector<int> solveB(int x) {
    vector<int> res;

    auto tmp = vfind(B, (n-x)/2);
    res.insert(res.end(), tmp.begin(), tmp.end());

    tmp = vfind(B, x);
    res.insert(res.end(), tmp.begin(), tmp.end());

    tmp = vfind(B, n-2*x);
    res.insert(res.end(), tmp.begin(), tmp.end());


    return res;
}

void dfs(int at, int p) {
    for (int ysiz: solveA(siz[at])) {
	int cur = get({siz[at], ysiz-siz[at], n-ysiz});
	lo = min(lo, cur);
    }

    for (int ysiz: solveB(siz[at])) {
	int cur = get({siz[at], ysiz, n-siz[at]-ysiz});
	lo = min(lo, cur);	
    }
    
    A.insert(siz[at]);
    
    for (int to: g[at]) {
	if (to == p) continue;
	dfs(to, at);
    }
    
    A.erase(A.find(siz[at]));
    B.insert(siz[at]);
}

int main() {
    ios_base::sync_with_stdio(false); cin.tie(0);  cout.tie(0);

    cin>>n;
    for (int i=0; i<n-1; i++) {
	int u,v; cin>>u>>v;
	g[u].push_back(v);
	g[v].push_back(u);
    }

    assert(n>=3);
    hack(1);

    lo = n;
    dfs(1,0);


    cout<<lo<<endl;    
    return 0;
}

Subtask #1
15.0 / 15.0

# 결과 실행 시간 메모리 Grader output
1 Correct 5 ms 5228 KB Output is correct
2 Correct 4 ms 5228 KB Output is correct
3 Correct 4 ms 5228 KB Output is correct
4 Correct 4 ms 5228 KB Output is correct
5 Correct 4 ms 5228 KB Output is correct

Subtask #2
35.0 / 35.0

# 결과 실행 시간 메모리 Grader output
1 Correct 5 ms 5228 KB Output is correct
2 Correct 4 ms 5228 KB Output is correct
3 Correct 4 ms 5228 KB Output is correct
4 Correct 4 ms 5228 KB Output is correct
5 Correct 4 ms 5228 KB Output is correct
6 Correct 9 ms 5484 KB Output is correct
7 Correct 10 ms 5484 KB Output is correct
8 Correct 8 ms 5484 KB Output is correct
9 Correct 9 ms 5612 KB Output is correct
10 Correct 9 ms 5484 KB Output is correct

Subtask #3
60.0 / 60.0

# 결과 실행 시간 메모리 Grader output
1 Correct 5 ms 5228 KB Output is correct
2 Correct 4 ms 5228 KB Output is correct
3 Correct 4 ms 5228 KB Output is correct
4 Correct 4 ms 5228 KB Output is correct
5 Correct 4 ms 5228 KB Output is correct
6 Correct 9 ms 5484 KB Output is correct
7 Correct 10 ms 5484 KB Output is correct
8 Correct 8 ms 5484 KB Output is correct
9 Correct 9 ms 5612 KB Output is correct
10 Correct 9 ms 5484 KB Output is correct
11 Correct 796 ms 38508 KB Output is correct
12 Correct 897 ms 38124 KB Output is correct
13 Correct 685 ms 41188 KB Output is correct
14 Correct 720 ms 40812 KB Output is correct
15 Correct 874 ms 40532 KB Output is correct
16 Correct 612 ms 40424 KB Output is correct
17 Correct 772 ms 40684 KB Output is correct
18 Correct 807 ms 47712 KB Output is correct
19 Correct 735 ms 40684 KB Output is correct
20 Correct 841 ms 40604 KB Output is correct