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Submission #68822

# Submission time Handle Problem Language Result Execution time Memory
68822 2018-08-18T16:28:58 Z 검수컵(#1978, imsifile) Island Traversal (FXCUP3_island) C++
100 / 100
 1270 ms 119460 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 32 ms 35960 KB Correct
2 Correct 32 ms 36072 KB Correct
3 Correct 33 ms 36156 KB Correct
4 Correct 33 ms 36192 KB Correct
5 Correct 33 ms 36192 KB Correct
6 Correct 44 ms 36244 KB Correct
7 Correct 43 ms 36300 KB Correct
8 Correct 34 ms 36300 KB Correct
9 Correct 34 ms 36300 KB Correct
10 Correct 38 ms 36300 KB Correct
11 Correct 33 ms 36300 KB Correct
12 Correct 40 ms 36300 KB Correct
13 Correct 36 ms 36596 KB Correct
14 Correct 35 ms 36596 KB Correct
15 Correct 41 ms 36596 KB Correct
16 Correct 34 ms 36596 KB Correct
17 Correct 39 ms 36596 KB Correct
18 Correct 35 ms 36596 KB Correct
19 Correct 34 ms 36596 KB Correct
20 Correct 37 ms 36596 KB Correct

Subtask #2
58.0 / 58.0

# Verdict Execution time Memory Grader output
1 Correct 32 ms 35960 KB Correct
2 Correct 32 ms 36072 KB Correct
3 Correct 33 ms 36156 KB Correct
4 Correct 33 ms 36192 KB Correct
5 Correct 33 ms 36192 KB Correct
6 Correct 44 ms 36244 KB Correct
7 Correct 43 ms 36300 KB Correct
8 Correct 34 ms 36300 KB Correct
9 Correct 34 ms 36300 KB Correct
10 Correct 38 ms 36300 KB Correct
11 Correct 33 ms 36300 KB Correct
12 Correct 40 ms 36300 KB Correct
13 Correct 36 ms 36596 KB Correct
14 Correct 35 ms 36596 KB Correct
15 Correct 41 ms 36596 KB Correct
16 Correct 34 ms 36596 KB Correct
17 Correct 39 ms 36596 KB Correct
18 Correct 35 ms 36596 KB Correct
19 Correct 34 ms 36596 KB Correct
20 Correct 37 ms 36596 KB Correct
21 Correct 295 ms 51068 KB Correct
22 Correct 635 ms 108520 KB Correct
23 Correct 513 ms 108520 KB Correct
24 Correct 505 ms 108520 KB Correct
25 Correct 773 ms 108544 KB Correct
26 Correct 517 ms 108544 KB Correct
27 Correct 324 ms 108544 KB Correct
28 Correct 144 ms 108544 KB Correct
29 Correct 803 ms 108544 KB Correct
30 Correct 1260 ms 119460 KB Correct
31 Correct 1270 ms 119460 KB Correct
32 Correct 76 ms 119460 KB Correct
33 Correct 185 ms 119460 KB Correct
34 Correct 1139 ms 119460 KB Correct
35 Correct 578 ms 119460 KB Correct