제출 #890633

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
890633		AgentPengin	꿈 (IOI13_dreaming)	C++17	100 / 100	93 ms	31852 KiB

dreaming

/**
 *    author:  AgentPengin ( Độc cô cầu bại )
 *    created: 23.12.2022 10:08:02
 *    too lazy to update time
**/
#include "dreaming.h"
#include<bits/stdc++.h>

#define EL '\n'
#define fi first
#define se second
#define NAME "TASK"
#define ll long long
#define lcm(a,b) (a/gcd(a,b))*b
#define db(val) "["#val" = " << (val) << "] "
#define bend(v) (v).begin(),(v).end()
#define sz(v) (int)(v).size()
#define ex exit(0)

using namespace std;

const ll mod = 1e9 + 7;
const int inf = 0x1FFFFFFF;
const int MAXN = 1e5 + 5;

struct Edges {
	int u,v,c;
};

int n,m,l,f[MAXN],ans = 0;
vector<pair<int,int>> adj[MAXN];
bool visited[MAXN];
vector<int> root;
pair<int,int> res;
vector<pair<int,int>> centroid;
vector<Edges> edges;

void dfs(int u,int p = 0) {
	visited[u] = true;
	if (p > 0) {
		pair<int,int> idx;
		for (auto x : adj[u]) {
			if (x.fi == p) {
				idx = x;
				break;
			}
		}
		adj[u].erase(find(bend(adj[u]),idx));
	}
	for (auto x : adj[u]) {
		int v = x.fi;
		int c = x.se;
		if (v == p) continue;
		dfs(v,u);
		f[u] = max(f[u],f[v] + c);
	}
}

void solve(int u,int p,int depth) {
	res = min(res,make_pair(max(depth,f[u]),u));
	ans = max(ans,depth + f[u]);
	// for (auto x : adj[u]) {
		// int v = x.fi;
		// int c = x.se;
// 		
	// }
	vector<int> prefix(sz(adj[u]),0),suffix(sz(adj[u]),0);
	for (int i = 0;i < sz(adj[u]);i++) {
		int v = adj[u][i].fi;
		int c = adj[u][i].se;
		if (i == 0) prefix[i] = f[v] + c;
		else prefix[i] = max(prefix[i - 1],f[v] + c);
	}
	for (int i = sz(adj[u]) - 1;i >= 0;i--) {
		int v = adj[u][i].fi;
		int c = adj[u][i].se;
		if (i == sz(adj[u]) - 1) suffix[i] = f[v] + c;
		else suffix[i] = max(suffix[i + 1],f[v] + c);
	}
	
	for (int i = 0;i < sz(adj[u]);i++) {
		int mx = 0;
		int v = adj[u][i].fi;
		int c = adj[u][i].se;
		if (i > 0) mx = max(mx,prefix[i - 1]);
		if (i < sz(adj[u]) - 1) mx = max(mx,suffix[i + 1]);
		solve(v,u,max(depth,mx) + c);
	}
}

pair<int,int> find_centroid(int Root) {
	ans = max(ans,f[Root]);
	res = make_pair(f[Root],Root);
	solve(Root,0,0);
	return res;
}

int travelTime(int N,int M,int L,int A[],int B[],int C[]) {
	n = N; m = M; l = L;
	for (int i = 0;i < m;i++) {
		A[i]++,B[i]++;
		adj[A[i]].push_back({B[i],C[i]});
		adj[B[i]].push_back({A[i],C[i]});		
		edges.push_back({A[i],B[i],C[i]});
	}
	
	// solve()
	for (int i = 1;i <= n;i++) {
    	if (!visited[i]) {
    		dfs(i,0);
    		root.push_back(i);
    	}
    }
    for (auto x : root) {
    	centroid.push_back(find_centroid(x));
    }
    sort(bend(centroid),greater<pair<int,int>>());
    for (int i = 1;i <= n;i++) adj[i].clear();
    for (int i = 1;i < sz(centroid);i++) {
    	edges.push_back({centroid[i].se,centroid[0].se,l});
    }
    for (auto x : edges) {
    	adj[x.u].push_back({x.v,x.c});
    	adj[x.v].push_back({x.u,x.c});
    }
    memset(visited,0,sizeof visited);
 	memset(f,0,sizeof f);
    dfs(1,0);
    pair<int,int> t = find_centroid(1);
    return ans;
}

컴파일 시 표준 에러 (stderr) 메시지

dreaming.cpp: In function 'int travelTime(int, int, int, int*, int*, int*)':
dreaming.cpp:129:19: warning: variable 't' set but not used [-Wunused-but-set-variable]
  129 |     pair<int,int> t = find_centroid(1);
      |                   ^

• Subtask 1: 14 / 14
• Subtask 2: 10 / 10
• Subtask 3: 23 / 23
• Subtask 4: 18 / 18
• Subtask 5: 12 / 12
• Subtask 6: 23 / 23