Submission #945832

#	Time	Username	Problem	Language	Result	Execution time	Memory
945832		vjudge1	Magic Tree (CEOI19_magictree)	C++17	0 / 100	87 ms	9420 KiB

magictree

#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("avx,avx2,fma")
#include <bits/stdc++.h>
 
#define ff first
#define ss second
#define pb push_back
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define rnd(l, r) uniform_int_distribution<int>(l, r)(rng)
 
using namespace std;
 
void fp(string name){freopen((name+".in").c_str(),"r",stdin); freopen((name+".out").c_str(),"w",stdout);} 
int pow(int a,int b,int m){int ans=1;while(b){if(b&1){ans=(ans*a)%m;}b>>=1;a=(a*a)%m;}return ans;}
int binpow(int a,int b){int ans=1;while(b){if(b&1){ans=(ans*a);}b>>=1;a=(a*a);}return ans;}
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
 
const int N = 1001, MX = 1e5 + 1;
 
int32_t tim[MX], cost[MX];
long long dp[MX], depth[N];
vector <int> g[MX];
int p[MX];

void dfs1(int v, int par){
	p[v] = par;
	for(auto to : g[v]){
		if(to == par)continue;
		depth[to] = depth[v] + 1;
		dfs1(to, v);
	}
}

void dfs(int v = 1, int time = 1){
	int c = 0;
	if(time == tim[v])c = cost[v];
	dp[v] = max(dp[v], c * 1ll);
	long long sum = 0;
	for(auto to : g[v]){
		if(to == p[v])continue;
		sum += dp[to];
	}
	dp[v] = max(dp[v], sum + c);
	if(v == 1)return;
	dfs(p[v], time);
}
 
main(){
	iostream::sync_with_stdio(false);	
    cin.tie(nullptr);
    cout.tie(nullptr);
    int n, m, k;
    cin >> n >> m >> k;
    for(int i = 2; i <= n; i++){
		int a;
		cin >> a;
		g[a].pb(i);
		g[i].pb(a);
	}
	dfs1(1, 1);
	vector < array <int32_t, 3> > vp;
	for(int i = 1 ; i<= m; i++){
		int a, b, c;
		cin >> a >> b >> c;
		vp.pb({b, a, c});
	}
	sort(all(vp));
	int cur = 0, prev =  -1;
	for(auto &[a, b, c] : vp){
		if(a != prev)cur++;
		prev = a;
		a = cur;
		swap(a, b);
	}
	for(auto &[a, b, c] : vp){
		cost[a] = c;
		tim[a] = b;
		swap(b, c);
		b = -depth[a];
	}
	sort(all(vp));
	for(auto &[a, b, c] : vp){
		dfs(a, c);
	}
	cout <<dp[1] << endl;
}	
/*
 * Before implementing the problem:
	
	Do I understand the problem correctly?
	Which places are tricky? What do I need to remember to implement them correctly?
	Which place is the heaviest by implementation? Can I do it simpler?
	Which place is the slowest? Where do I need to be careful about constant factors and where I can choose slower but simpler implementation?
	----------------------------------
	If not AC:
 
	Did you remember to do everything to handle the tricky places you thought about before?
	Is the solution correct?
	Do I understand the problem correctly?
	----------------------------------
	If you have a test on which the solution gives wrong answer:
 
	Is the solution doing what it was supposed to do?
	Is the problem in the code or in the idea?
*/

Compilation message (stderr)

magictree.cpp:49:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   49 | main(){
      | ^~~~
magictree.cpp: In function 'void fp(std::string)':
magictree.cpp:14:29: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   14 | void fp(string name){freopen((name+".in").c_str(),"r",stdin); freopen((name+".out").c_str(),"w",stdout);}
      |                      ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
magictree.cpp:14:70: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   14 | void fp(string name){freopen((name+".in").c_str(),"r",stdin); freopen((name+".out").c_str(),"w",stdout);}
      |                                                               ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 6
• Subtask 2: 0 / 3
• Subtask 3: 0 / 11
• Subtask 4: 0 / 12
• Subtask 5: 0 / 16
• Subtask 6: 0 / 13
• Subtask 7: 0 / 22
• Subtask 8: 0 / 17