oj.uz

Submission #68821

# Submission time Handle Problem Language Result Execution time Memory
68821 2018-08-18T16:23:50 Z imsifile Island Traversal (FXCUP3_island) C++
100 / 100
 1273 ms 119648 KB 
#include<stdio.h>
#include<algorithm>
#include<vector>
#include<queue>
using namespace std;

int N, in, iix, lcn[303030], deg[303030];
vector<int> fir[303030], leaf[303030], tree[303030], ins;
vector<pair<int,int> > con[303030], inv[303030]; int concn, invcn;

void edge(vector<pair<int,int> > *v, int s, int e, int &ecn){
	v[s].push_back(make_pair(e,ecn));
	v[e].push_back(make_pair(s,ecn));
	ecn++;
}

void divide(){
	for(int i=1; i<=N; i++){
		if(deg[i] > N-1-deg[i]) iix=i;
		if(deg[i] > 1){
			in++, ins.push_back(i);
			for(int j=fir[i].size(); j--;){
				int e=fir[i][j];
				if(deg[e]==1) leaf[i].push_back(e), lcn[i]++;
				else tree[i].push_back(e);
			}
		}
	}
}

int tmp[303030], dap;
vector<int> bw[2];
void eachin(int s, int e) { edge(inv, s, e, invcn), deg[s]--, deg[e]--, dap++; }

void dfs1(int s, int ix, int col){
	tmp[ix]=1;
	if(ix!=s) bw[col].push_back(ix);
	for(int i=tree[ix].size(); i--;){
		int e=tree[ix][i];
		if(!tmp[e]) dfs1(s, e, col^1);
	}
}

void color_tree(int s){
	if(s == -1){
		dfs1(-1, ins[0], 0);
		if(bw[0].size() <= 2){
			int sz = bw[0].size();
			for(int i=0; i<sz-1; i++) eachin(bw[0][i], bw[0][i+1]);
			sz = bw[1].size();
			for(int i=0; i<sz; i++) eachin(bw[1][i], bw[1][(i+1)%sz]);
		}
		else{
			int sz = bw[1].size();
			for(int i=0; i<sz-1; i++) eachin(bw[1][i], bw[1][i+1]);
			sz = bw[0].size();
			for(int i=0; i<sz; i++) eachin(bw[0][i], bw[0][(i+1)%sz]);
		}
		return;
	}

	int left=in-1;
	for(int i=tree[s].size(); i--;) tmp[tree[s][i]] = 1;
	for(int i=0; i<in; i++){
		int e=ins[i];
		if(tmp[e]==0 && s!=e) eachin(s, e), left--;
		tmp[e]=0;
	}
	if(left >= 3){
		int sz=tree[s].size();
		for(int i=0; i<sz; i++){
			int a=tree[s][i], b=tree[s][(i+1)%sz];
			eachin(a, b);
		}
		return;
	}
	dfs1(s, s, 1);
	if(left == 1){
		if(bw[0].size() >= 2) eachin(bw[0][0], bw[0][1]);
		else eachin(bw[1][0], bw[1][1]);
	}
	else{
		eachin(bw[0][0], bw[0][1]);
		if(bw[0].size() >= 3) eachin(bw[0][0], bw[0][2]);
		else eachin(bw[1][0], bw[1][1]);
	}
}

vector<int> lin;
void dfs2(int ix){
	tmp[ix]=1;
	lin.push_back(ix);
	for(int i=tree[ix].size(); i--;){
		int e=tree[ix][i];
		if(!tmp[e]) dfs2(e);
	}
}

void line_tree(int s){
	dfs2(s);
	int sz=lin.size();
	eachin(lin[0], lin[sz-1]);
	for(int i=0; i<sz-2; i+=2) eachin(lin[i], lin[i+2]);
	for(int i=1; i<sz-2; i+=2) eachin(lin[i], lin[i+2]);
}

struct my {
	int sum, ix;
	my(int sum_=0, int ix_=0){ sum=sum_, ix=ix_; }
	bool operator< (const my &c) const {
		return sum < c.sum;
	}
};

priority_queue<my> ld, l0, d0;
void push(int s){
	my m(lcn[s]+deg[s], s);
	if(lcn[s]>0 && deg[s]>0) ld.push(m);
	if(lcn[s]==0 && deg[s]>0) l0.push(m);
	if(lcn[s]>0 && deg[s]==0) d0.push(m);
}
void eachmatch(int d, int l){
	deg[d]--, lcn[l]--;
	edge(inv, d, leaf[l][lcn[l]], invcn); dap++;
}

void match(){
	for(int i=0; i<in; i++) push(ins[i]);
	while(!ld.empty()){
		my s=ld.top(), e;
		ld.pop();
		if(!ld.empty()) e=ld.top(), ld.pop();
		else if(!d0.empty()) e=d0.top(), d0.pop();
		else e=l0.top(), l0.pop(), swap(s, e);
		eachmatch(s.ix, e.ix);
		push(s.ix); push(e.ix);
	}
	while(!l0.empty()){
		my s=l0.top(); l0.pop();
		my e=d0.top(); d0.pop();
		eachmatch(s.ix, e.ix);
		push(s.ix); push(e.ix);
	}
}

int cjs[303030], ijs[303030];
int cchk[303030], ichk[303030];
void get_euler(int s, int typ){
	if(typ){
		while(cjs[s] < con[s].size()){
			pair<int,int> im=con[s][cjs[s]++];
			int e=im.first, eix=im.second;
			if(cchk[eix]) continue;
			cchk[eix]=1;
			get_euler(e, typ^1);
		}
	}
	else{
		while(ijs[s] < inv[s].size()){
			pair<int,int> im=inv[s][ijs[s]++];
			int e=im.first, eix=im.second;
			if(ichk[eix]) continue;
			ichk[eix]=1;
			get_euler(e, typ^1);
		}
	}
	printf("%d ", s);
}

int main(){
	scanf("%d", &N);
	for(int i=0; i<N-1; i++){
		int s, e;
		scanf("%d%d", &s, &e);
		fir[s].push_back(e), fir[e].push_back(s);
		deg[s]++, deg[e]++;
	}
	divide();
	if(in <= 1){ puts("0"); return 0; }
	if(in == 2){
		int a=ins[0], b=ins[1];
		int mi = min(lcn[a],lcn[b]);
		lcn[a]=lcn[b]=deg[a]=deg[b]=mi;
		for(int i=0; i<mi; i++){
			edge(con, a, leaf[a][i], concn);
			edge(con, b, leaf[b][i], concn);
		}
	}
	else if(in == 3){
		if(iix){
			int oth = N-1-deg[iix];
			lcn[iix]=oth+1-tree[iix].size(), deg[iix]=oth+1;
		}
		int a=-1, b=-1, c=-1;
		iix = ins[0];
		for(int i=0; i<3; i++){
			if(deg[iix] < deg[ins[i]]) iix=ins[i];
			if(tree[ins[i]].size() == 2) b=ins[i];
			else if(a<0) a=ins[i];
			else c=ins[i];
		}
		for(int j=0; j<lcn[a]; j++) edge(con, a, leaf[a][j], concn);
		for(int j=0; j<lcn[b]; j++) edge(con, b, leaf[b][j], concn);
		for(int j=0; j<lcn[c]; j++) edge(con, c, leaf[c][j], concn);

		eachin(a, c);
		if(iix==a || iix==b){
			deg[a]--, deg[b]--;
			edge(con, b, c, concn);
		}
		if(iix==c){
			deg[c]--, deg[b]--;
			edge(con, b, a, concn);
		}
	}
	else{
		if(iix){
			int oth = N-1-deg[iix];
			lcn[iix]=oth-tree[iix].size(), deg[iix]=oth;
		}
		for(int i=0; i<in; i++){
			int s=ins[i];
			for(int j=0; j<lcn[s]; j++) edge(con, s, leaf[s][j], concn);
			for(int j=tree[s].size(); j--;){
				if(s < tree[s][j]) edge(con, s, tree[s][j], concn);
			}
		}
		if(in == 4){
			for(int i=0; i<in; i++){
				int s=ins[i];
				for(int j=tree[s].size(); j--;) tmp[tree[s][j]] = 1;
				for(int j=i+1; j<in; j++){
					if(tmp[ins[j]]==0) eachin(s, ins[j]);
				}
				for(int j=tree[s].size(); j--;) tmp[tree[s][j]] = 0;
			}
		}
		else{
			int lsum=0, ovc=0, ovi;
			for(int i=0; i<in; i++) lsum += lcn[ins[i]];
			for(int i=0; i<in; i++){
				int s=ins[i];
				if(deg[s]+lcn[s] > lsum) ovc++, ovi=s;
			}
			if(ovc==0) color_tree(-1);
			else if(ovc==1) color_tree(ovi);
			else line_tree(ovi);
		}
	}
	match();
	printf("%d\n", dap*2);
	get_euler(ins[0], 1);
	return 0;
}

Compilation message

island.cpp: In function 'void get_euler(int, int)':
island.cpp:150:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   while(cjs[s] < con[s].size()){
         ~~~~~~~^~~~~~~~~~~~~~~
island.cpp:159:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   while(ijs[s] < inv[s].size()){
         ~~~~~~~^~~~~~~~~~~~~~~
island.cpp: In function 'int main()':
island.cpp:171:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &N);
  ~~~~~^~~~~~~~~~
island.cpp:174:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", &s, &e);
   ~~~~~^~~~~~~~~~~~~~~~

Subtask #1
42.0 / 42.0

# Verdict Execution time Memory Grader output
1 Correct 35 ms 35960 KB Correct
2 Correct 36 ms 36072 KB Correct
3 Correct 34 ms 36072 KB Correct
4 Correct 40 ms 36332 KB Correct
5 Correct 42 ms 36332 KB Correct
6 Correct 37 ms 36332 KB Correct
7 Correct 37 ms 36332 KB Correct
8 Correct 31 ms 36332 KB Correct
9 Correct 31 ms 36332 KB Correct
10 Correct 31 ms 36332 KB Correct
11 Correct 32 ms 36332 KB Correct
12 Correct 33 ms 36332 KB Correct
13 Correct 40 ms 36492 KB Correct
14 Correct 32 ms 36492 KB Correct
15 Correct 32 ms 36492 KB Correct
16 Correct 38 ms 36492 KB Correct
17 Correct 32 ms 36492 KB Correct
18 Correct 34 ms 36492 KB Correct
19 Correct 36 ms 36492 KB Correct
20 Correct 36 ms 36492 KB Correct

Subtask #2
58.0 / 58.0

# Verdict Execution time Memory Grader output
1 Correct 35 ms 35960 KB Correct
2 Correct 36 ms 36072 KB Correct
3 Correct 34 ms 36072 KB Correct
4 Correct 40 ms 36332 KB Correct
5 Correct 42 ms 36332 KB Correct
6 Correct 37 ms 36332 KB Correct
7 Correct 37 ms 36332 KB Correct
8 Correct 31 ms 36332 KB Correct
9 Correct 31 ms 36332 KB Correct
10 Correct 31 ms 36332 KB Correct
11 Correct 32 ms 36332 KB Correct
12 Correct 33 ms 36332 KB Correct
13 Correct 40 ms 36492 KB Correct
14 Correct 32 ms 36492 KB Correct
15 Correct 32 ms 36492 KB Correct
16 Correct 38 ms 36492 KB Correct
17 Correct 32 ms 36492 KB Correct
18 Correct 34 ms 36492 KB Correct
19 Correct 36 ms 36492 KB Correct
20 Correct 36 ms 36492 KB Correct
21 Correct 274 ms 51080 KB Correct
22 Correct 615 ms 108492 KB Correct
23 Correct 515 ms 108492 KB Correct
24 Correct 432 ms 108492 KB Correct
25 Correct 708 ms 108492 KB Correct
26 Correct 541 ms 108492 KB Correct
27 Correct 359 ms 108492 KB Correct
28 Correct 161 ms 108492 KB Correct
29 Correct 889 ms 108492 KB Correct
30 Correct 1273 ms 119648 KB Correct
31 Correct 1106 ms 119648 KB Correct
32 Correct 100 ms 119648 KB Correct
33 Correct 194 ms 119648 KB Correct
34 Correct 1161 ms 119648 KB Correct
35 Correct 611 ms 119648 KB Correct