Submission #264800

#	Time	Username	Problem	Language	Result	Execution time	Memory
264800		shayan_p	Fireworks (APIO16_fireworks)	C++14	7 / 100	3 ms	2688 KiB

fireworks

// only miss the sun when it starts to snow
 
#include<bits/stdc++.h>
 
#define F first
#define S second
#define PB push_back
#define sz(s) int((s).size())
#define bit(n,k) (((n)>>(k))&1)
 
using namespace std;
 
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
 
const int maxn=1e5+10,mod=1e9+7;
const ll inf=1e18;
 
vector<pii> v[maxn];
vector<ll> vec;
pll s[maxn];
ll ans;
 
void dfs(int u){
    for(pii p:v[u]){
	dfs(p.F);
	s[p.F].F+= p.S;
	s[p.F].S+= p.S;
    }
    vec.clear();
    ll num=0;
    for(pii p:v[u]){
	num+= s[p.F].S - s[p.F].F;
	vec.PB( s[p.F].F ), vec.PB( s[p.F].S );
    }
    sort(vec.begin(), vec.end() );
    if(sz(vec)){
	int mid=sz(vec)/2;
	s[u]={ vec[mid-1], vec[mid] };
 
	num = -num;
      
	for(ll x:vec){
	    num+= abs( s[u].F - x );
	}
    
    ans+= num/2;
    }
}
 
int main(){
    ios_base::sync_with_stdio(false); cin.tie(0); cout.tie();
 
    int n,m; cin>>n>>m;
 
    for(int i=1;i<n+m;i++){
	int x,y; cin>>x>>y;
	v[--x].PB({i,y});
    }
    dfs(0);
    return cout<< ans <<endl,0;
}
// Deathly mistakes:
//  * Read the problem carefully.
//  * Check maxn.
//  * Overflows.
 
 
// #pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

• Subtask 1: 7 / 7
• Subtask 2: 0 / 19
• Subtask 3: 0 / 29
• Subtask 4: 0 / 45