Submission #142646

#	Time	Username	Problem	Language	Result	Execution time	Memory
142646		RafaelSus	Transport (COCI19_transport)	C++14	52 / 130	1068 ms	18544 KiB

Main

#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
 
using namespace std;
const int maxn = 1e5 + 5;
 
int n, a[maxn], w[maxn];
vector <pair<int, long long>> g[maxn];
int used[maxn];
 
long long dp1[maxn], ben1[maxn];
long long dp2[maxn], ben2[maxn]; 
int sz[maxn];
long long answ;
                         
void sizeCounter(int v, int p){
    sz[v] = 1;       
    dp1[v] = dp2[v] = 0; 
    ben1[v] = ben2[v] = 0;
    for (int i = 0; i < g[v].size(); i++){
        int to = g[v][i].first;
        if (to == p || used[to]) continue;
        sizeCounter(to, v);      
        sz[v] += sz[to];     
    }                    
}                        
                         
                         
int center = 0;          
void findCen(int v, int p, int cnt){
	int ok = 1;
	for (int i = 0; i < g[v].size(); i++){
		int to = g[v][i].first;
		if (to == p || used[to]) continue;
        if (sz[to] - 1 >= cnt){
            ok = 1;
            findCen(to, v, cnt);
          	break;
		}
	}
  	if (ok == 0) center = v;
}
 
vector <long long> G; 
 
void push_DP(int v, int p){
	sz[v] = 1;	
	for (int i = 0; i < g[v].size(); i++){
		int to = g[v][i].first;
		int len = g[v][i].second;
		if (to == p || used[to]) continue;
 
		ben1[to] = ben1[v] + a[v] - len;
		dp1[to] = dp1[v];
		if (ben1[to] < 0){
			dp1[to] -= ben1[to];
			ben1[to] = 0;
		} 	
		
		int d = a[to] - len;
		dp2[to] = dp2[v] + d;
		ben2[to] = min(1ll * d, ben2[v] + d);
		
		push_DP(to, v);
		sz[v] += sz[to];
	}
 
	if (ben2[v] >= 0){
		G.push_back(dp2[v]);
	}		
}
 
int findCenter(int v){
	sizeCounter(v, -1);
	center = v;
	findCen(v, -1, (sz[v] - 1) / 2);
	push_DP(center, -1);	
	return center;
}
 
 
vector <long long> P;
vector <int> ver;
 
void solve(int v, int p){
 
	if (p != -1){
		ver.push_back(v);
		if (ben2[v] >= 0){
			P.push_back(dp2[v]);	
		}	
	}
		
	int idx = lower_bound(G.begin(), G.end(), dp1[v]) - G.begin();
	answ += (int)G.size() - idx;
	if (p == -1) answ--;
	
	for (int i = 0; i < g[v].size(); i++){
		int to = g[v][i].first;
		if (to == p || used[to]) continue;
		solve (to, v);
		if (p == -1){
			sort (P.begin(), P.end());
			for (int j = 0; j < ver.size(); j++){
				int u = ver[j];
				int id = lower_bound(P.begin(), P.end(), dp1[u]) - P.begin();
				answ -= (int)P.size() - id;	
			}	
			P.clear();
			ver.clear();
		}	
	}
}
 
void centroidDecomposition() {
	queue <int> q;
	q.push(1);
	while (!q.empty()) {
		int v = q.front();
		q.pop();
		v = findCenter(v);
		sort(G.begin(), G.end());
		solve(v, -1);
		G.clear();
		
		for (int i = 0; i < g[v].size(); i++){
			int to = g[v][i].first;
			if (used[to] || sz[to] == 1) continue;
			q.push(to);	
		}
		used[v] = 1;
	}
}

int main() {
 
	ios::sync_with_stdio(false);
	cin.tie(0);
 
	scanf("%d", &n);
	for (int i = 1; i <= n; i++)
		scanf("%d", &a[i]);
	for (int i = 0; i < n - 1; i++) {
		int x, y, z;
      	scanf("%d%d%d", &x, &y, &z);
		g[x].push_back({ y, z });
		g[y].push_back({ x, z });
	}
 
	centroidDecomposition();
	printf("%lld\n", answ);
	return 0;
}

Compilation message (stderr)

transport.cpp: In function 'void sizeCounter(int, int)':
transport.cpp:22:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < g[v].size(); i++){
                     ~~^~~~~~~~~~~~~
transport.cpp: In function 'void findCen(int, int, int)':
transport.cpp:34:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < g[v].size(); i++){
                  ~~^~~~~~~~~~~~~
transport.cpp: In function 'void push_DP(int, int)':
transport.cpp:50:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < g[v].size(); i++){
                  ~~^~~~~~~~~~~~~
transport.cpp: In function 'void solve(int, int)':
transport.cpp:100:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < g[v].size(); i++){
                  ~~^~~~~~~~~~~~~
transport.cpp:106:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for (int j = 0; j < ver.size(); j++){
                    ~~^~~~~~~~~~~~
transport.cpp: In function 'void centroidDecomposition()':
transport.cpp:128:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < g[v].size(); i++){
                   ~~^~~~~~~~~~~~~
transport.cpp: In function 'int main()':
transport.cpp:142:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &n);
  ~~~~~^~~~~~~~~~
transport.cpp:144:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &a[i]);
   ~~~~~^~~~~~~~~~~~~
transport.cpp:147:13: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
        scanf("%d%d%d", &x, &y, &z);
        ~~~~~^~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 13 / 13
• Subtask 2: 13 / 13
• Subtask 3: 0 / 13
• Subtask 4: 0 / 13
• Subtask 5: 0 / 13
• Subtask 6: 0 / 13
• Subtask 7: 0 / 13
• Subtask 8: 13 / 13
• Subtask 9: 13 / 13
• Subtask 10: 0 / 13