Submission #887167

#	Time	Username	Problem	Language	Result	Execution time	Memory
887167		MilosMilutinovic	Pipes (BOI13_pipes)	C++14	30 / 100	366 ms	131072 KiB

pipes

#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,n) for (int i=a;i<n;i++)
#define per(i,a,n) for (int i=n-1;i>=a;i--)
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
typedef vector<int> VI;
typedef basic_string<int> BI;
typedef long long ll;
typedef pair<int,int> PII;
typedef double db;
mt19937 mrand(random_device{}()); 
const ll mod=998244353;
int rnd(int x) { return mrand() % x;}
ll powmod(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
// head

const int N=100100;

int n,m,c[N],res[N];
vector<PII> e[N];

void dfs(int v,int f) {
	for (auto u:e[v]) {
		if (u.fi==f) continue;
		dfs(u.fi,v);
		c[v]-=c[u.fi];
		res[u.se]=c[u.fi];
	}
}

int main() {
	scanf("%d%d",&n,&m);
	rep(i,1,n+1) scanf("%d",&c[i]);
	rep(i,1,m+1) {
		int u,v;
		scanf("%d%d",&u,&v);
		e[u].pb(mp(v,i)); e[v].pb(mp(u,i));
	}
	dfs(1,1);
	if (c[1]==0) {
		rep(i,1,m+1) printf("%d\n",2*res[i]);
	} else {
		printf("0\n");
	}
}

Compilation message (stderr)

pipes.cpp: In function 'int main()':
pipes.cpp:39:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   39 |  scanf("%d%d",&n,&m);
      |  ~~~~~^~~~~~~~~~~~~~
pipes.cpp:40:20: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   40 |  rep(i,1,n+1) scanf("%d",&c[i]);
      |               ~~~~~^~~~~~~~~~~~
pipes.cpp:43:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   43 |   scanf("%d%d",&u,&v);
      |   ~~~~~^~~~~~~~~~~~~~

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