Submission #1045328

#	Time	Username	Problem	Language	Result	Execution time	Memory
1045328		_rain_	Transport (COCI19_transport)	C++14	130 / 130	164 ms	25524 KiB

Main

#include<bits/stdc++.h>
using namespace std;
#define int long long
using i64 = long long;
const int maxn = 2e5;
std::vector<pair<int,i64>> graph[maxn+2];
int a[maxn+2] , n;

	i64 BIT[maxn+2];
	void upd(int pos , int val)
	{
		for (; pos <= maxn;  pos += pos&-pos)
			BIT[pos] += val;
		return;
	}
	i64 get(int id)
	{
		i64 sum = 0;
		for (; id ; id -= id&-id)
			sum += BIT[id];
		return sum;
	}
	i64 sum_range(int l , int r)
	{
		return get(r) - get(l);
	}


	int sub[maxn+2] ;
	bool mark[maxn+2];
	std::vector<pair<i64,int>> cost;
	std::vector<i64> down;
	int id[maxn+2];
	i64 answer = 0;

	int get_centroid(int v , int p , int half)
	{
		for (auto& xx : graph[v])
		{
			int to = xx.first , w = xx.second;	
			if (mark[to] || to == p) continue;
			if (sub[to] > half) return get_centroid(to,v,half);
		}
		return v;
	}

	void dfssize(int v , int p)
	{
		sub[v]=1;
		for (auto& xx : graph[v])
		{
			int to = xx.first , w = xx.second;	
			if (to==p||mark[to]) continue;
			dfssize(to,v);
			sub[v]+=sub[to];
		}
		return;
	}

	void downforces(int v , int p , i64 mn , i64 used)
	{
			down.push_back(mn);
			for (auto& xx : graph[v])
			{
				int to = xx.first , w = xx.second;	
				if (mark[to] || to == p) continue;
				downforces(to , v , min({mn , used + a[v] - w }) , used + a[v] - w);
			}
			return;
	}

	void build(int v , int p , i64 sum , i64 mncost)
	{
		if (mncost >= 0)
				cost.push_back({sum , v});
		for (auto& xx : graph[v])
		{
			int to = xx.first , w = xx.second;	
			if (to==p || mark[to]) continue;
			build(to , v , sum + a[to] - w , min(mncost + a[to] - w , a[to] - w));
		}
		return;
	}

	void centroid(int v)
	{
		dfssize(v,v);
		v = get_centroid(v,v,sub[v]/2);
		mark[v] = true;

		// DP 
			for (auto& xx : graph[v])
			{
				int to = xx.first , w = xx.second;	
				if (mark[to]) continue;
				build(to , v , a[to] - w , a[to] - w);
			}
			
			vector<i64> allcost ;
			std::sort(cost.begin() , cost.end());
			for (int i = 0; i < cost.size(); ++i)
			{
				id[cost[i].second] = i + 1;
				upd(i+1 , 1);
				allcost.push_back(cost[i].first);
				++answer;
			}
			cost.clear();

			for (auto& xx : graph[v])
			{
				int to = xx.first , w = xx.second;	
				if (mark[to]) continue;
				// cout << "VERTEX IS : " << to << '\n';
				build(to , v , a[to] - w , a[to] - w);
				for (auto& yy: cost) 
					{
						int y = yy.second;
						upd(id[y] , -1);
					}
					downforces(to , v , a[v] - w , a[v] - w);
					for (auto& x : down)
					{
						if (x >= 0) ++answer;
						int pos = lower_bound(allcost.begin() , allcost.end() , -x) - allcost.begin() ;
						answer += sum_range(pos , allcost.size());
					}
					down.clear();
				for (auto& yy: cost) 
					{
						int y = yy.second;
						upd(id[y] , 1);
					}
				cost.clear();
			}

			for (int i = 0; i < allcost.size(); ++i) upd(i + 1 , -1);
		
		for (auto& xx : graph[v])
		{
			int to = xx.first , w = xx.second;
			if (!mark[to]) centroid(to);
		}
	}

int32_t main()
{
	ios_base::sync_with_stdio(0);
	cin.tie(0); cout.tie(0);

	cin >> n ;
	for (int i = 1; i <= n; ++i) cin >> a[i];
	for (int i = 1; i < n; ++i)
	{
		int u , v , w; cin >> u >> v >> w;
		graph[u].push_back({v , w});
		graph[v].push_back({u , w});
	}
	centroid(1);
	cout << answer;
}

Compilation message (stderr)

transport.cpp: In function 'long long int get_centroid(long long int, long long int, long long int)':
transport.cpp:40:24: warning: unused variable 'w' [-Wunused-variable]
   40 |    int to = xx.first , w = xx.second;
      |                        ^
transport.cpp: In function 'void dfssize(long long int, long long int)':
transport.cpp:52:24: warning: unused variable 'w' [-Wunused-variable]
   52 |    int to = xx.first , w = xx.second;
      |                        ^
transport.cpp: In function 'void centroid(long long int)':
transport.cpp:101:22: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  101 |    for (int i = 0; i < cost.size(); ++i)
      |                    ~~^~~~~~~~~~~~~
transport.cpp:137:22: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  137 |    for (int i = 0; i < allcost.size(); ++i) upd(i + 1 , -1);
      |                    ~~^~~~~~~~~~~~~~~~
transport.cpp:141:24: warning: unused variable 'w' [-Wunused-variable]
  141 |    int to = xx.first , w = xx.second;
      |                        ^

• Subtask 1: 13 / 13
• Subtask 2: 13 / 13
• Subtask 3: 13 / 13
• Subtask 4: 13 / 13
• Subtask 5: 13 / 13
• Subtask 6: 13 / 13
• Subtask 7: 13 / 13
• Subtask 8: 13 / 13
• Subtask 9: 13 / 13
• Subtask 10: 13 / 13