Submission #106155

#	Time	Username	Problem	Language	Result	Execution time	Memory
106155		luciocf	Pipes (BOI13_pipes)	C++14	0 / 100	1084 ms	132096 KiB

pipes

#include <bits/stdc++.h>

using namespace std;

const int maxn = 1e5+10;
const int maxm = 5e5+10;

typedef pair<int, int> pii;

int a[maxn], cur[maxn];

int edge[maxn], costEdge[maxm];

vector<pii> grafo[maxn];

void dfs(int u, int p)
{
	for (auto pp: grafo[u])
	{
		int v = pp.first, e = pp.second;
		if (v == p) continue;

		edge[v] = e;

		dfs(v, u);

		cur[u] += costEdge[e];
	}

	if (u != 1)
	{
		costEdge[edge[u]] = (a[u]-cur[u]);
		cur[u] = a[u];
	}
}

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

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

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

		grafo[u].push_back({v, i});
		grafo[v].push_back({u, i});
	}

	dfs(1, 0);

	if (cur[1] != a[1]) printf("0\n");
	else
	{
		for (int i = 1; i <= m; i++)
			printf("%d\n", costEdge[i]);
	}
}

Compilation message (stderr)

pipes.cpp: In function 'int main()':
pipes.cpp:40:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d", &n, &m);
  ~~~~~^~~~~~~~~~~~~~~~~
pipes.cpp:43:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &a[i]);
   ~~~~~^~~~~~~~~~~~~
pipes.cpp:48:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d", &u, &v);
   ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 30
• Subtask 2: 0 / 70