Submission #115416

#	Time	Username	Problem	Language	Result	Execution time	Memory
115416		shashwatchandra	Pipes (BOI13_pipes)	C++17	74.07 / 100	103 ms	15480 KiB

pipes

/*input
4 3
-1
1
-3
1
1 2
1 3
1 4
*/
#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;

#define int long long 
#define double long double
#define f first
#define s second
#define mp make_pair
#define pb push_back

#define RE(i,n) for (int i = 1; i <= n; i++)
#define RED(i,n) for (int i = n; i > 0; i--)
#define REPS(i,n) for(int i = 1; (i*i) <= n; i++)
#define REP(i,n) for (int i = 0; i < (int)n; i++)
#define FOR(i,a,b) for (int i = a; i < b; i++)
#define REPD(i,n) for (int i = n-1; i >= 0; i--)
#define FORD(i,a,b) for (int i = a; i >= b; i--)

#define all(v) v.begin(),v.end()
#define pii pair<int,int>
#define vi vector<int>
#define vvi vector<vi>
#define print(arr) for (auto it = arr.begin(); it != arr.end(); ++it) cout << *it << " "; cout << endl;
#define debug(x) cout << x << endl;
#define debug2(x,y) cout << x << " " << y << endl;
#define debug3(x,y,z) cout << x << " " << y << " " << z << endl;

typedef tree<
int,
null_type,
less<int>,
rb_tree_tag,
tree_order_statistics_node_update>
ordered_set;

const int INF = 1e18+1;
const int MOD = 1e9+7;
const double PI = 3.14159265358979323846264338;

int raise(int a,int n,int m = MOD){
  if(n == 0)return 1;
  if(n == 1)return a;
  int x = 1;
    x *= raise(a,n/2,m);
    x %= m;
    x *= x;
    x %= m;
    if(n%2)x*= a;
    x %= m;
    return x;
}

int floor1(int n,int k){
    if(n%k == 0 || n >= 0)return n/k;
    return (n/k)-1;
}

int ceil1(int n,int k){
    return floor1(n+k-1,k);
}

const int N = 1e5+1;
vector<pii> adj[N];
int n,m;
int c[N];
int now[N];
int dep[N];
vector<pii> edges;
map<pii,int> val;
bool works = 0;
bool vis[N];
int ans[5*N];
int even = 0;
bool odd = 0;

void dfs(int u,int p,int ind = -1){
	if(vis[u])return;
	vis[u] = 1;
	for(auto v:adj[u]){
		if(!vis[v.f])dep[v.f] = dep[u]+1;
		else{
			if(v.f == p)continue;
			if(abs(dep[v.f]-dep[u])%2)odd = 1;
			else {
				//cout << u << " " << v << endl;
				even++;
				ans[v.s] = 0;
			}
		}
		dfs(v.f,u,v.s);
	}
	if(p == -1){
		if(!odd)works = (now[u] == c[u]);
		return;
	}
	int diff = c[u]-now[u];
	//cout << u 3<< " " << diff << endl;
	now[p] += diff;
	ans[ind] = 2*diff;
	return;
}

void solve(){
  	cin >> n >> m;
  	if(m > n){
  		cout << 0;
  		return;
  	}
  	RE(i,n)cin >> c[i];
  	RE(i,m){
  		int a,b;
  		cin >> a >> b;
  		adj[a].pb({b,i});
  		adj[b].pb({a,i});
  	}
  	dep[1] = 0;
  	dfs(1,-1);
  	if(odd or !works){
  		cout << 0 << endl;
  		return;
  	}
  	RE(i,m){
  		cout << ans[i] << "\n";
  	}
}

signed main(){
  ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
  //freopen(".in","r",stdin);freopen(".out","w",stdout);
  int t = 1;
  //cin >> t;
  while(t--){
    solve();
  }
  return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 44.074074074074076 / 70