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Submission #303943

# Submission time Handle Problem Language Result Execution time Memory
303943 2020-09-20T19:59:18 Z peuch One-Way Streets (CEOI17_oneway) C++17
100 / 100
 229 ms 33272 KB 
#include<bits/stdc++.h>
using namespace std;

const int MAXN = 100010;

int n, m, p;
int low[MAXN], pre[MAXN];
int cnt;
int bridge[MAXN];
pair<int, int> edge[MAXN];

int rep[MAXN], tam[MAXN];

int auxSum[MAXN];
int marc[MAXN];

int ans[MAXN];

vector<int> ar[MAXN], id[MAXN];
vector<int> tree[MAXN], treeID[MAXN];

void dfs(int cur, int pai);
void uni(int a, int b);
int find(int a);
void endCalc(int cur, int pai);

int main(){
	
	scanf("%d %d", &n, &m);
	for(int i = 1; i <= n; i++) rep[i] = i, tam[i] = 1;
	for(int i = 1; i <= m; i++){
		int a, b;
		scanf("%d %d", &a, &b);
		ar[a].push_back(b);
		ar[b].push_back(a);
		id[a].push_back(i);
		id[b].push_back(i);
		edge[i] = make_pair(a, b);
	}
	
	for(int i = 1; i <= n; i++)
		if(marc[i] != 1) dfs(i, 0);
	
	for(int i = 1; i <= m; i++){
		if(bridge[i]) continue;
		uni(edge[i].first, edge[i].second);
	}
	
	for(int i = 1; i <= m; i++){
		if(!bridge[i]) continue;
		int a = edge[i].first;
		int b = edge[i].second;
		a = find(a);
		b = find(b);
		tree[a].push_back(b);
		tree[b].push_back(a);
		treeID[a].push_back(i);
		treeID[b].push_back(i);
	}
	
	scanf("%d", &p);
	for(int i = 1; i <= p; i++){
		int a, b;
		scanf("%d %d", &a, &b);
		a = find(a);
		b = find(b);
		auxSum[a]++;
		auxSum[b]--;
	}
	
	
	for(int i = 1; i <= n; i++)
		if(marc[find(i)] != 2) endCalc(find(i), 0);
	for(int i = 1; i <= m; i++){
		if(ans[i] == 1) printf("R");
		else if(ans[i] == -1) printf("L");
		else printf("B");
	}
	printf("\n");
	return 0;
}

void dfs(int cur, int pai){
	marc[cur] = 1;
	pre[cur] = low[cur] = ++cnt;
	for(int i = 0; i < ar[cur].size(); i++){
		int viz = ar[cur][i];
		if(id[cur][i] == pai) continue;
		if(pre[viz] != 0) low[cur] = min(low[cur], pre[viz]);
		else{
			dfs(viz, id[cur][i]);
			if(low[viz] > pre[cur]) bridge[id[cur][i]] = 1;
			low[cur] = min(low[cur], low[viz]);
		}
	}
}

void uni(int a, int b){
	a = find(a);
	b = find(b);
	if(a == b) return;
	if(tam[a] > tam[b])
		tam[a] += tam[b], rep[b] = a;	
	else
		tam[b] += tam[a], rep[a] = b;	
}

int find(int a){
	if(rep[a] == a) return a;
	return rep[a] = find(rep[a]);
}

void endCalc(int cur, int pai){
	marc[cur] = 2; 
	for(int i = 0; i < tree[cur].size(); i++){
		int viz = tree[cur][i];
		int eID = treeID[cur][i];
		if(viz == pai) continue;
		endCalc(viz, cur);
		if(auxSum[viz] < 0){
			if(find(edge[eID].first) == cur) ans[eID] = 1;
			else ans[eID] = -1;
		}
		else if(auxSum[viz] > 0){
			if(find(edge[eID].first) == cur) ans[eID] = -1;
			else ans[eID] = 1;
		}
		auxSum[cur] += auxSum[viz];
	}
}

Compilation message

oneway.cpp: In function 'void dfs(int, int)':
oneway.cpp:86:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   86 |  for(int i = 0; i < ar[cur].size(); i++){
      |                 ~~^~~~~~~~~~~~~~~~
oneway.cpp: In function 'void endCalc(int, int)':
oneway.cpp:115:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  115 |  for(int i = 0; i < tree[cur].size(); i++){
      |                 ~~^~~~~~~~~~~~~~~~~~
oneway.cpp: In function 'int main()':
oneway.cpp:29:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   29 |  scanf("%d %d", &n, &m);
      |  ~~~~~^~~~~~~~~~~~~~~~~
oneway.cpp:33:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   33 |   scanf("%d %d", &a, &b);
      |   ~~~~~^~~~~~~~~~~~~~~~~
oneway.cpp:61:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   61 |  scanf("%d", &p);
      |  ~~~~~^~~~~~~~~~
oneway.cpp:64:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   64 |   scanf("%d %d", &a, &b);
      |   ~~~~~^~~~~~~~~~~~~~~~~

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 9728 KB Output is correct
2 Correct 6 ms 9728 KB Output is correct
3 Correct 7 ms 9856 KB Output is correct
4 Correct 7 ms 9856 KB Output is correct
5 Correct 7 ms 9984 KB Output is correct
6 Correct 7 ms 9856 KB Output is correct
7 Correct 7 ms 9984 KB Output is correct
8 Correct 7 ms 9984 KB Output is correct
9 Correct 7 ms 9856 KB Output is correct
10 Correct 7 ms 9856 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 9728 KB Output is correct
2 Correct 6 ms 9728 KB Output is correct
3 Correct 7 ms 9856 KB Output is correct
4 Correct 7 ms 9856 KB Output is correct
5 Correct 7 ms 9984 KB Output is correct
6 Correct 7 ms 9856 KB Output is correct
7 Correct 7 ms 9984 KB Output is correct
8 Correct 7 ms 9984 KB Output is correct
9 Correct 7 ms 9856 KB Output is correct
10 Correct 7 ms 9856 KB Output is correct
11 Correct 75 ms 16376 KB Output is correct
12 Correct 89 ms 18040 KB Output is correct
13 Correct 103 ms 19960 KB Output is correct
14 Correct 127 ms 22904 KB Output is correct
15 Correct 145 ms 24184 KB Output is correct
16 Correct 214 ms 27512 KB Output is correct
17 Correct 147 ms 29176 KB Output is correct
18 Correct 184 ms 27896 KB Output is correct
19 Correct 134 ms 30328 KB Output is correct
20 Correct 79 ms 17912 KB Output is correct
21 Correct 77 ms 18552 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 9728 KB Output is correct
2 Correct 6 ms 9728 KB Output is correct
3 Correct 7 ms 9856 KB Output is correct
4 Correct 7 ms 9856 KB Output is correct
5 Correct 7 ms 9984 KB Output is correct
6 Correct 7 ms 9856 KB Output is correct
7 Correct 7 ms 9984 KB Output is correct
8 Correct 7 ms 9984 KB Output is correct
9 Correct 7 ms 9856 KB Output is correct
10 Correct 7 ms 9856 KB Output is correct
11 Correct 75 ms 16376 KB Output is correct
12 Correct 89 ms 18040 KB Output is correct
13 Correct 103 ms 19960 KB Output is correct
14 Correct 127 ms 22904 KB Output is correct
15 Correct 145 ms 24184 KB Output is correct
16 Correct 214 ms 27512 KB Output is correct
17 Correct 147 ms 29176 KB Output is correct
18 Correct 184 ms 27896 KB Output is correct
19 Correct 134 ms 30328 KB Output is correct
20 Correct 79 ms 17912 KB Output is correct
21 Correct 77 ms 18552 KB Output is correct
22 Correct 185 ms 30328 KB Output is correct
23 Correct 192 ms 28792 KB Output is correct
24 Correct 229 ms 29048 KB Output is correct
25 Correct 171 ms 33272 KB Output is correct
26 Correct 168 ms 29944 KB Output is correct
27 Correct 173 ms 28792 KB Output is correct
28 Correct 65 ms 13920 KB Output is correct
29 Correct 108 ms 18680 KB Output is correct
30 Correct 111 ms 19576 KB Output is correct
31 Correct 114 ms 19064 KB Output is correct
32 Correct 128 ms 24312 KB Output is correct