Submission #143905

#	Time	Username	Problem	Language	Result	Execution time	Memory
143905		onjo0127	Split the Attractions (IOI19_split)	C++14	40 / 100	194 ms	19192 KiB

split

#include "split.h"
#include <bits/stdc++.h>
using namespace std;

const int MXN = 100009;
bool vs[MXN];
vector<int> G[MXN], T[MXN];
int N, M, F1 = 1, F2 = 2, F3 = 3, A, B, C, sz[MXN], P[MXN], ans[MXN], cent, U[MXN], S[MXN];

int root(int x) {
    if(U[x] == x) return x;
    return U[x] = root(U[x]);
}

void merg(int u, int v) {
    u = root(u); v = root(v);
    if(u != v) U[u] = v, S[v] += S[u];
}

void dfs1(int x) {
    vs[x] = 1; sz[x] = 1;
    for(auto& it: G[x]) if(!vs[it]) {
        dfs1(it);
        sz[x] += sz[it];
        T[x].push_back(it);
        T[it].push_back(x);
    }
}

int fnd(int rt, int x) {
    int mxi = -1;
    for(auto &it: T[x]) {
        if(sz[it] > sz[x]) continue;
        if(mxi == -1 || sz[mxi] < sz[it]) mxi = it;
    }
    if(mxi == -1 || sz[mxi] * 2 <= sz[rt]) return x;
    return fnd(rt, mxi);
}

void dfs2(int x, int p) {
    sz[x] = 1; P[x] = p;
    for(auto& it: T[x]) if(it != p) {
        dfs2(it, x);
        sz[x] += sz[it];
    }
}

int lft;
void grd(int x, int p, int bck, int col) {
    if(!lft || ans[x]) return;
    ans[x] = col; --lft;
    if(bck) for(auto& it: G[x]) grd(it, x, bck, col);
    else for(auto& it: T[x]) if(it != p) grd(it, x, bck, col);
}

vector<int> makeans(bool fail) {
    if(fail) {
        vector<int> res(N, 0);
        return res;
    }
    vector<int> res(N, F3);
    for(int i=0; i<N; i++) {
        if(ans[i] == 1) res[i] = F1;
        if(ans[i] == 2) res[i] = F2;
    }
    return res;
}

void bfs(int st) {
    int cnt = 0;
    deque<int> que; que.push_back(st); ans[st] = -1;
    while(cnt < A) {
        int x = que.front(); que.pop_front();
        ans[x] = 1; ++cnt;
        for(auto& it: T[x]) {
            if(it == cent) continue;
            if(!ans[it]) {
                ans[it] = -1;
                que.push_front(it);
            }
        }
        for(auto& it: G[x]) {
            if(it == cent) continue;
            if(!ans[it]) {
                ans[it] = -1;
                que.push_back(it);
            }
        }
    }
    for(int i=0; i<N; i++) if(ans[i] == -1) ans[i] = 0;
}

vector<int> find_split(int n, int a, int b, int c, vector<int> p, vector<int> q) {
	if(a > b) swap(a, b), swap(F1, F2);
	if(a > c) swap(a, c), swap(F1, F3);
    if(b > c) swap(b, c), swap(F2, F3);
    A = a; B = b; C = c; N = n; M = p.size();
    for(int i=0; i<M; i++) {
        G[p[i]].push_back(q[i]);
        G[q[i]].push_back(p[i]);
    }
    dfs1(0);
    cent = fnd(0, 0);
    dfs2(cent, cent);
    for(int i=0; i<N; i++) {
        if(i == cent) continue;
        if(sz[i] >= A && N - sz[i] >= B) {
            lft = A; grd(i, P[i], 0, 1);
            lft = B; grd(P[i], P[i], 1, 2);
            return makeans(0);
        }
    }
    for(int i=0; i<N; i++) S[i] = 1, U[i] = i;
    for(int i=0; i<M; i++) {
        if(p[i] == cent || q[i] == cent) continue;
        merg(p[i], q[i]);
    }
    int st = -1;
    for(auto& it: T[cent]) if(S[root(it)] >= A) st = it;
    if(st == -1) return makeans(1);
    bfs(st);
    lft = B; grd(cent, cent, 1, 2);
	return makeans(0);
}

• Subtask 1: 7 / 7
• Subtask 2: 11 / 11
• Subtask 3: 22 / 22
• Subtask 4: 0 / 24
• Subtask 5: 0 / 36