Submission #417585

#	Time	Username	Problem	Language	Result	Execution time	Memory
417585		ja_kingy	Split the Attractions (IOI19_split)	C++14	100 / 100	284 ms	31164 KiB

split

#include "split.h"
#include <bits/stdc++.h>

using namespace std;
typedef pair<int,int> pii;
const int mxN = 1e5, INF = 1e9;
vector<int> adj[mxN], t[mxN], cg[mxN], ans;
int n, seen1[mxN], bst_mx=INF, bst_u, bst_v, dsu[mxN], sz[mxN];
int f(int x) {return dsu[x] != x ? dsu[x] = f(dsu[x]) : x;}

int dfs1(int u, int p) {
	seen1[u] = 1;
	int sm = 1, mx = 0, bv = 0;
	for (int v: adj[u]) {
		if (!seen1[v]) {
			t[u].push_back(v);
			t[v].push_back(u);
			int res = dfs1(v, u);
			sm += res;
			if (res > mx) {
				bv = v;
				mx = res;
			}
		}
	}
	int res = n-sm;
	if (res > mx) {
		bv = p;
		mx = res;
	}
	if (mx < bst_mx) {
		bst_mx = mx;
		bst_u = u;
		bst_v = bv;
	}
	return sm;
}

void dfs2(int u, pii &cc, vector<int>* g) {
	if (cc.first) {
		cc.first--;
		ans[u] = cc.second;
	} else return;
	for (int v: g[u]) if (!ans[v]) {
		dfs2(v, cc, g);
	}
}

void merge(int a, int b) {
	cg[a].push_back(b);
	cg[b].push_back(a);
	a = f(a), b = f(b);
	if (a != b) {
		if (sz[b] > sz[a]) swap(a,b);
		dsu[b] = a;
		sz[a] += sz[b];
	}
}

vector<int> find_split(int _n, int a, int b, int c, vector<int> p, vector<int> q) {
	n = _n;
	pii ccs[3] = {{a,1},{b,2},{c,3}};
	sort(ccs, ccs+3);
	ans.resize(n);
    for (int i  = 0; i < p.size(); ++i) {
		adj[p[i]].push_back(q[i]);
		adj[q[i]].push_back(p[i]);
	}
	dfs1(0,0);
	if (bst_mx >= ccs[0].first) {
		ans[bst_u] = ccs[1].second;
		dfs2(bst_v, ccs[0], t);
		dfs2(bst_u, ccs[1], t);
	} else {
		bool valid = 0;
		iota(dsu, dsu+n, 0);
		fill(sz, sz+n, 1);
		for (int u = 0; u < n; ++u) for (int v: t[u]) {
			if (u != bst_u && v != bst_u) merge(u, v);
		}
		for (int u = 0; u < n && !valid; ++u) for (int v: adj[u]) {
			if (u != bst_u && v != bst_u) merge(u, v);
			if (sz[f(u)] >= ccs[0].first) {
				valid = 1;
				dfs2(u, ccs[0], cg);
				dfs2(bst_u, ccs[1], t);
				break;
			}
		}
		if (!valid) return ans;
	}
	for (int i = 0; i < n; ++i) if (!ans[i]) ans[i] = ccs[2].second;
	return ans;
}

Compilation message (stderr)

split.cpp: In function 'std::vector<int> find_split(int, int, int, int, std::vector<int>, std::vector<int>)':
split.cpp:65:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   65 |     for (int i  = 0; i < p.size(); ++i) {
      |                      ~~^~~~~~~~~~

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