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Submission #63209

# Submission time Handle Problem Language Result Execution time Memory
63209 2018-08-01T05:58:44 Z 김세빈(#1833) Alternating Current (BOI18_alternating) C++11
0 / 100
 3000 ms 18000 KB 
#include <bits/stdc++.h>

using namespace std;

typedef pair <int, int> pii;

vector <int> L[101010], V[101010];
vector <int> X[101010], Y[101010];
set <int> S;
pii P[101010];
int chk[101010], ans[101010];
int fff[101010];
int n, m;

void die() { printf("impossible\n"); exit(0); }

void dfs(int p, int c)
{
	chk[p] = 2; ans[p] = c;
	for(int &t: V[p]){
		if(chk[t] == 1) dfs(t, !c);
		else if(ans[t] == ans[p]) die();
	}
}

int main()
{
	int i, s, e, x, y, a, b;
	
	scanf("%d%d", &n, &m);
	
	for(i=1; i<=m; i++){
		scanf("%d%d", &a, &b);
		b ++; if(b > n) b -= n;
		P[i] = pii(a, b);
		if(a < b){
			L[a].push_back(i);
			L[b].push_back(-i);
		}
		else{
			L[1].push_back(i);
			L[b].push_back(-i);
			L[a].push_back(i);
		}
	}
	
	for(i=1; i<=n; i++){
		for(int &t: L[i]){
			if(t > 0) S.insert(t);
			else S.erase(-t);
		}
		
		if(S.size() == 2){
			a = *S.begin(); b = *next(S.begin());
			V[a].push_back(b);
			V[b].push_back(a);
			chk[a] = 1; chk[b] = 1;
		}
		else if(S.size() == 1) die();
	}
	
	for(i=1; i<=m; i++){
		if(chk[i] == 1) dfs(i, 0);
	}
	
	x = 1;
	
	for(i=1; i<=m; i++){
		if(chk[i]){
			if(ans[i] == 1){
				X[P[i].first].push_back(i);
				x = i;
			}
		}
		else Y[P[i].first].push_back(i);
	}
	
	ans[x] = 1;
	s = P[x].first, e = P[x].second;
	
	for(i=s; ; ){
		for(int &t: X[i]){
			if(P[t].first < P[t].second){
				if(i <= e && e < P[t].second) e = P[t].second;
			}
			else{
				if(i <= e) e = P[t].second;
				else if(e < P[t].second) e = P[t].second;
			}
		}
		for(int &t: Y[i]) y = t;
		
		if(i == e){
			ans[y] = 1;
			e = P[y].second;
			i = P[y].first;
		}
		
		i ++; if(i > n) i -= n;
		if(i == s) break;
	}
	
	for(i=1; i<=m; i++){
		if(ans[i] == 0){
			if(P[i].first < P[i].second){
				for(int j=P[i].first; j<P[i].second; j++) fff[j] = 1;
			}
			else{
				for(int j=P[i].first; j<=n; j++) fff[j] = 1;
				for(int j=1; j<P[i].second; j++) fff[j] = 1;
			}
		}
	}
	
	for(i=1; i<=n; i++){
		if(!fff[i]) die();
		fff[i] = 0;
	}
	
	for(i=1; i<=m; i++) printf("%d", ans[i]);
	printf("\n");
	
	return 0;
}

Compilation message

alternating.cpp: In function 'int main()':
alternating.cpp:30:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &n, &m);
  ~~~~~^~~~~~~~~~~~~~~~
alternating.cpp:33:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", &a, &b);
   ~~~~~^~~~~~~~~~~~~~~~
alternating.cpp:96:13: warning: 'y' may be used uninitialized in this function [-Wmaybe-uninitialized]
    i = P[y].first;
        ~~~~~^~~~~

Subtask #1
0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 11 ms 9848 KB Output is correct
2 Correct 11 ms 9920 KB Output is correct
3 Correct 11 ms 9920 KB Output is correct
4 Correct 12 ms 9960 KB Output is correct
5 Correct 11 ms 9960 KB Output is correct
6 Correct 11 ms 10064 KB Output is correct
7 Correct 12 ms 10064 KB Output is correct
8 Correct 11 ms 10064 KB Output is correct
9 Correct 13 ms 10064 KB Output is correct
10 Correct 11 ms 10064 KB Output is correct
11 Correct 11 ms 10064 KB Output is correct
12 Correct 11 ms 10064 KB Output is correct
13 Correct 14 ms 10064 KB Output is correct
14 Correct 13 ms 10064 KB Output is correct
15 Correct 13 ms 10064 KB Output is correct
16 Execution timed out 3030 ms 10072 KB Time limit exceeded
17 Halted 0 ms 0 KB -

Subtask #2
0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 11 ms 9848 KB Output is correct
2 Correct 11 ms 9920 KB Output is correct
3 Correct 11 ms 9920 KB Output is correct
4 Correct 12 ms 9960 KB Output is correct
5 Correct 11 ms 9960 KB Output is correct
6 Correct 11 ms 10064 KB Output is correct
7 Correct 12 ms 10064 KB Output is correct
8 Correct 11 ms 10064 KB Output is correct
9 Correct 13 ms 10064 KB Output is correct
10 Correct 11 ms 10064 KB Output is correct
11 Correct 11 ms 10064 KB Output is correct
12 Correct 11 ms 10064 KB Output is correct
13 Correct 14 ms 10064 KB Output is correct
14 Correct 13 ms 10064 KB Output is correct
15 Correct 13 ms 10064 KB Output is correct
16 Execution timed out 3030 ms 10072 KB Time limit exceeded
17 Halted 0 ms 0 KB -

Subtask #3
0 / 22.0

# Verdict Execution time Memory Grader output
1 Correct 11 ms 9848 KB Output is correct
2 Correct 11 ms 9920 KB Output is correct
3 Correct 11 ms 9920 KB Output is correct
4 Correct 12 ms 9960 KB Output is correct
5 Correct 11 ms 9960 KB Output is correct
6 Correct 11 ms 10064 KB Output is correct
7 Correct 12 ms 10064 KB Output is correct
8 Correct 11 ms 10064 KB Output is correct
9 Correct 13 ms 10064 KB Output is correct
10 Correct 11 ms 10064 KB Output is correct
11 Correct 11 ms 10064 KB Output is correct
12 Correct 11 ms 10064 KB Output is correct
13 Correct 14 ms 10064 KB Output is correct
14 Correct 13 ms 10064 KB Output is correct
15 Correct 13 ms 10064 KB Output is correct
16 Execution timed out 3030 ms 10072 KB Time limit exceeded
17 Halted 0 ms 0 KB -

Subtask #4
0 / 19.0

# Verdict Execution time Memory Grader output
1 Execution timed out 3100 ms 18000 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #5
0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 11 ms 9848 KB Output is correct
2 Correct 11 ms 9920 KB Output is correct
3 Correct 11 ms 9920 KB Output is correct
4 Correct 12 ms 9960 KB Output is correct
5 Correct 11 ms 9960 KB Output is correct
6 Correct 11 ms 10064 KB Output is correct
7 Correct 12 ms 10064 KB Output is correct
8 Correct 11 ms 10064 KB Output is correct
9 Correct 13 ms 10064 KB Output is correct
10 Correct 11 ms 10064 KB Output is correct
11 Correct 11 ms 10064 KB Output is correct
12 Correct 11 ms 10064 KB Output is correct
13 Correct 14 ms 10064 KB Output is correct
14 Correct 13 ms 10064 KB Output is correct
15 Correct 13 ms 10064 KB Output is correct
16 Execution timed out 3030 ms 10072 KB Time limit exceeded
17 Halted 0 ms 0 KB -