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Submission #297244

# Submission time Handle Problem Language Result Execution time Memory
297244 2020-09-11T12:14:02 Z Lawliet Pipes (BOI13_pipes) C++17
100 / 100
 402 ms 27640 KB 
#include <bits/stdc++.h>

using namespace std;
typedef long long int lli;

const int MAXN = 100010;
const int MAXM = 500010;

int n, m;

int v[MAXN];
int degree[MAXN];

lli ans[MAXM];
lli curSum[MAXN];

bool mark[MAXN];

vector<int> adj[MAXN];
vector<int> indEdge[MAXN];

queue<int> q;

void add(int cur)
{
	q.push(cur);
	mark[cur] = true;
}

int nextIndEdge(int cur)
{
	for(int i = 0 ; i < (int)adj[cur].size() ; i++)
		if( !mark[ adj[cur][i] ] ) return i;

	return -1;
}

lli getDiff(int cur) { return v[cur] - curSum[cur]; }

void topologicalSorting()
{
	for(int i = 1 ; i <= n ; i++)
		if( degree[i] == 1 ) add( i );

	while( !q.empty() )
	{
		int cur = q.front();
		q.pop();

		int nxtInd = nextIndEdge( cur );

		int anc = adj[cur][nxtInd];
		int ind = indEdge[cur][nxtInd];

		ans[ind] = getDiff(cur);
		curSum[cur] += ans[ind]; curSum[anc] += ans[ind];

		if( --degree[anc] == 1 )
			add( anc );
	}
}

void addEdge(int U, int V, int i)
{
	adj[U].push_back( V );
	adj[V].push_back( U );

	indEdge[U].push_back( i );
	indEdge[V].push_back( i );

	degree[U]++; degree[V]++;
}

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

void printAnswer()
{
	for(int i = 1 ; i <= m ; i++)
		printf("%lld\n",2*ans[i]);
}

void findAnswerCycle()
{
	int rootCycle;

	for(int i = 1 ; i <= n ; i++)
		if( !mark[i] ) rootCycle = i;

	int cur = rootCycle;

	vector<int> cycleNodes;
	vector<int> cycleEdges;

	while( !mark[cur] )
	{
		mark[cur] = true;
		cycleNodes.push_back( cur );

		int nxtInd = nextIndEdge( cur );

		if( nxtInd == -1 ) break;
		
		cycleEdges.push_back( indEdge[cur][nxtInd] );
		cur = adj[cur][nxtInd];
	}

	for(int i = 0 ; i < (int)adj[cur].size() ; i++)
		if( adj[cur][i] == rootCycle ) cycleEdges.push_back( indEdge[cur][i] );

	lli sumCycle = 0;
	int szCycle = (int)cycleNodes.size();

	if( szCycle%2 == 0 ) notUnique();

	for(int i = 0 ; i < szCycle ; i++)
		sumCycle += getDiff( cycleNodes[i] );

	sumCycle /= 2;

	lli sumPrefix[] = { 0 , 0 };
	lli sumSuffix[] = { 0 , 0 };

	for(int i = 0 ; i < szCycle ; i++)
		sumSuffix[i%2] += getDiff( cycleNodes[i] );

	for(int i = 0 ; i < szCycle ; i++)
	{
		sumPrefix[i%2] += getDiff( cycleNodes[i] );
		sumSuffix[i%2] -= getDiff( cycleNodes[i] );

		ans[ cycleEdges[i] ] = sumCycle - sumPrefix[1 - i%2] - sumSuffix[i%2];
	}
}

int main()
{
	scanf("%d %d",&n,&m);

	for(int i = 1 ; i <= n ; i++)
		scanf("%d",&v[i]);

	for(int i = 1 ; i <= m ; i++)
	{
		int U, V;
		scanf("%d %d",&U,&V);

		addEdge( U , V , i );
	}

	if( m > n ) notUnique();

	if( m == n - 1 ) addEdge( 1 , 1 , n );
	
	topologicalSorting();

	if( m == n ) findAnswerCycle();
	printAnswer();
}

Compilation message

pipes.cpp: In function 'int main()':
pipes.cpp:141:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  141 |  scanf("%d %d",&n,&m);
      |  ~~~~~^~~~~~~~~~~~~~~
pipes.cpp:144:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  144 |   scanf("%d",&v[i]);
      |   ~~~~~^~~~~~~~~~~~
pipes.cpp:149:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  149 |   scanf("%d %d",&U,&V);
      |   ~~~~~^~~~~~~~~~~~~~~
pipes.cpp: In function 'void findAnswerCycle()':
pipes.cpp:98:18: warning: 'rootCycle' may be used uninitialized in this function [-Wmaybe-uninitialized]
   98 |  while( !mark[cur] )
      |          ~~~~~~~~^

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 4992 KB Output is correct
2 Correct 4 ms 4992 KB Output is correct
3 Correct 5 ms 5120 KB Output is correct
4 Correct 135 ms 16128 KB Output is correct
5 Correct 4 ms 4992 KB Output is correct
6 Correct 4 ms 5120 KB Output is correct
7 Correct 4 ms 4992 KB Output is correct
8 Correct 4 ms 4992 KB Output is correct
9 Correct 4 ms 5120 KB Output is correct
10 Correct 4 ms 5120 KB Output is correct
11 Correct 5 ms 5120 KB Output is correct
12 Correct 4 ms 5120 KB Output is correct
13 Correct 100 ms 13848 KB Output is correct
14 Correct 122 ms 15480 KB Output is correct
15 Correct 128 ms 16264 KB Output is correct
16 Correct 109 ms 14584 KB Output is correct
17 Correct 132 ms 16088 KB Output is correct
18 Correct 155 ms 16088 KB Output is correct
19 Correct 135 ms 15784 KB Output is correct
20 Correct 4 ms 4992 KB Output is correct
21 Correct 4 ms 5120 KB Output is correct
22 Correct 133 ms 16216 KB Output is correct
23 Correct 97 ms 13816 KB Output is correct
24 Correct 128 ms 16216 KB Output is correct
25 Correct 104 ms 14456 KB Output is correct

Subtask #2
70.0 / 70.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 4992 KB Output is correct
2 Correct 5 ms 5120 KB Output is correct
3 Correct 110 ms 15480 KB Output is correct
4 Correct 97 ms 13688 KB Output is correct
5 Correct 95 ms 13560 KB Output is correct
6 Correct 400 ms 27512 KB Output is correct
7 Correct 4 ms 4992 KB Output is correct
8 Correct 4 ms 4992 KB Output is correct
9 Correct 4 ms 4992 KB Output is correct
10 Correct 4 ms 4992 KB Output is correct
11 Correct 4 ms 4992 KB Output is correct
12 Correct 4 ms 5120 KB Output is correct
13 Correct 4 ms 4992 KB Output is correct
14 Correct 4 ms 4992 KB Output is correct
15 Correct 4 ms 5120 KB Output is correct
16 Correct 4 ms 5120 KB Output is correct
17 Correct 4 ms 5120 KB Output is correct
18 Correct 4 ms 5120 KB Output is correct
19 Correct 4 ms 5120 KB Output is correct
20 Correct 4 ms 5120 KB Output is correct
21 Correct 5 ms 5120 KB Output is correct
22 Correct 5 ms 5120 KB Output is correct
23 Correct 104 ms 14156 KB Output is correct
24 Correct 136 ms 16052 KB Output is correct
25 Correct 110 ms 15484 KB Output is correct
26 Correct 99 ms 13688 KB Output is correct
27 Correct 97 ms 13560 KB Output is correct
28 Correct 113 ms 13816 KB Output is correct
29 Correct 351 ms 23928 KB Output is correct
30 Correct 129 ms 15736 KB Output is correct
31 Correct 132 ms 16200 KB Output is correct
32 Correct 128 ms 16112 KB Output is correct
33 Correct 118 ms 15996 KB Output is correct
34 Correct 100 ms 13688 KB Output is correct
35 Correct 103 ms 13816 KB Output is correct
36 Correct 101 ms 13816 KB Output is correct
37 Correct 402 ms 27640 KB Output is correct
38 Correct 130 ms 16004 KB Output is correct
39 Correct 127 ms 16064 KB Output is correct
40 Correct 127 ms 16056 KB Output is correct
41 Correct 114 ms 16200 KB Output is correct
42 Correct 95 ms 13688 KB Output is correct
43 Correct 100 ms 13688 KB Output is correct
44 Correct 94 ms 13560 KB Output is correct
45 Correct 287 ms 23616 KB Output is correct
46 Correct 135 ms 15924 KB Output is correct
47 Correct 127 ms 16068 KB Output is correct
48 Correct 131 ms 16372 KB Output is correct
49 Correct 105 ms 15096 KB Output is correct
50 Correct 96 ms 13944 KB Output is correct
51 Correct 103 ms 13688 KB Output is correct
52 Correct 95 ms 13564 KB Output is correct
53 Correct 355 ms 24184 KB Output is correct
54 Correct 137 ms 15912 KB Output is correct