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Submission #74271

# Submission time Handle Problem Language Result Execution time Memory
74271 2018-08-30T17:04:39 Z georgerapeanu Beads and wires (APIO14_beads) C++11
100 / 100
 267 ms 21572 KB 
#include <cstdio>
#include <vector>
#include <algorithm>

using namespace std;

FILE *f = stdin;
FILE *g = stdout;

struct edge_t{
	int to,cost;
	
	edge_t(){
		to = cost = 0;
	}
	
	edge_t(int to,int cost){
		this->to = to;
		this->cost = cost;
	}
};

const int NMAX = 2e5;

int n;
vector<edge_t> graph[NMAX + 5];
int dp[NMAX + 5][2];
int best_nodes[NMAX + 5][2];
int best_cost[NMAX + 5][2];
int ans;



void dfs1(int nod,int tata,int cost_tata){
	dp[nod][0] = dp[nod][1] = 0;
	best_nodes[nod][0] = best_nodes[nod][1] = 0;
	int best_upgrade_cost = -(1 << 30);
	int best_upgrade_cost2 = -(1 << 30);
	for(auto it:graph[nod]){
		if(it.to == tata){
			continue;
		}
		dfs1(it.to,nod,it.cost);
		dp[nod][0] += max(dp[it.to][0],dp[it.to][1]);
		int it_cost_to_upgrade = dp[it.to][0] - max(dp[it.to][0],dp[it.to][1]) + it.cost;
		if(it_cost_to_upgrade > best_upgrade_cost){
			best_upgrade_cost2 = best_upgrade_cost;
			best_nodes[nod][1] = best_nodes[nod][0];
			best_upgrade_cost = it_cost_to_upgrade;
			best_nodes[nod][0]= it.to;
		}
		else if(it_cost_to_upgrade > best_upgrade_cost2){
			best_upgrade_cost2 = it_cost_to_upgrade;
			best_nodes[nod][1]= it.to;
		}
	}
	
	best_cost[nod][0] = best_upgrade_cost;
	best_cost[nod][1] = best_upgrade_cost2;
	
	if(tata){
		if(best_upgrade_cost == -(1 << 30)){
			dp[nod][1] = -(1 << 30);
		}
		else{
			dp[nod][1] = dp[nod][0] + best_upgrade_cost + cost_tata;
		}
	}
	
	else{
		if(best_upgrade_cost2 == -(1 << 30)){
			dp[nod][1] = -(1 << 30);
		}
		else{
			dp[nod][1] = dp[nod][0] + best_upgrade_cost + best_upgrade_cost2;
		}
	}
	
}

void dfs2(int nod,int tata){
	ans = max(ans,dp[nod][0]);
	ans = max(ans,dp[nod][1]);
	
	int back_son[2];
	int back[2] = {dp[nod][0],dp[nod][1]};
	
	for(auto it:graph[nod]){
		if(it.to == tata){
			continue;
		}
		
		back_son[0] = dp[it.to][0];
		back_son[1] = dp[it.to][1];
		
		dp[nod][0] -= max(dp[it.to][0],dp[it.to][1]);
		if(it.to == best_nodes[nod][0] || it.to == best_nodes[nod][1]){
			if(best_cost[nod][1] != -(1 << 30)){
				dp[nod][1] -= dp[it.to][0];
			}
			else{
				dp[nod][1] = -(1 << 30);
			}
		}
		else{
			if(best_cost[nod][1] == -(1 << 30)){
				dp[nod][1] = -(1 << 30);
			}
			else{
				dp[nod][1] = dp[nod][1] - max(dp[it.to][0],dp[it.to][1]) - best_cost[nod][1] + it.cost;
			}
		}
		
		dp[it.to][0] += max(dp[nod][0],dp[nod][1]);
		int nod_cost = dp[nod][0] - max(dp[nod][0],dp[nod][1]) + it.cost;
		
		if(best_cost[it.to][0] < nod_cost){
			best_cost[it.to][1] = best_cost[it.to][0];
			best_nodes[it.to][1] = best_nodes[it.to][0];
			best_cost[it.to][0] = nod_cost;
			best_nodes[it.to][0] = nod;
		}
		
		else if(best_cost[it.to][1] < nod_cost){
			best_cost[it.to][1] = nod_cost;
			best_nodes[it.to][1] = nod;
		}
		
		if(best_cost[it.to][1] == -(1 << 30)){
			dp[it.to][1] = -(1 << 30);
		}
		else{
			dp[it.to][1] = dp[it.to][0] + best_cost[it.to][0] + best_cost[it.to][1];
		}
		
		dfs2(it.to,nod);
		
		dp[it.to][0] = back_son[0];
		dp[it.to][1] = back_son[1];
		dp[nod][0] = back[0];
		dp[nod][1] = back[1];
		
	}
}

int main(){
	
	fscanf(f,"%d",&n);
	
	for(int i = 1;i < n;i++){
		int a,b,c;
		fscanf(f,"%d %d %d",&a,&b,&c);
		graph[a].push_back(edge_t(b,c));
		graph[b].push_back(edge_t(a,c));
	}
	
	dfs1(1,0,0);
	dfs2(1,0);
	
	fprintf(g,"%d",ans);
	
	return 0;
}

Compilation message

beads.cpp: In function 'int main()':
beads.cpp:148:8: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  fscanf(f,"%d",&n);
  ~~~~~~^~~~~~~~~~~
beads.cpp:152:9: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   fscanf(f,"%d %d %d",&a,&b,&c);
   ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
13.0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 4948 KB Output is correct
2 Correct 5 ms 4992 KB Output is correct
3 Correct 5 ms 4992 KB Output is correct
4 Correct 5 ms 4992 KB Output is correct
5 Correct 5 ms 4992 KB Output is correct
6 Correct 5 ms 4992 KB Output is correct
7 Correct 6 ms 4992 KB Output is correct
8 Correct 5 ms 4992 KB Output is correct
9 Correct 5 ms 4992 KB Output is correct
10 Correct 6 ms 4992 KB Output is correct
11 Correct 5 ms 4992 KB Output is correct
12 Correct 5 ms 4992 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 4948 KB Output is correct
2 Correct 5 ms 4992 KB Output is correct
3 Correct 5 ms 4992 KB Output is correct
4 Correct 5 ms 4992 KB Output is correct
5 Correct 5 ms 4992 KB Output is correct
6 Correct 5 ms 4992 KB Output is correct
7 Correct 6 ms 4992 KB Output is correct
8 Correct 5 ms 4992 KB Output is correct
9 Correct 5 ms 4992 KB Output is correct
10 Correct 6 ms 4992 KB Output is correct
11 Correct 5 ms 4992 KB Output is correct
12 Correct 5 ms 4992 KB Output is correct
13 Correct 5 ms 5120 KB Output is correct
14 Correct 5 ms 4992 KB Output is correct
15 Correct 5 ms 4992 KB Output is correct
16 Correct 5 ms 4992 KB Output is correct
17 Correct 5 ms 4992 KB Output is correct
18 Correct 6 ms 4992 KB Output is correct
19 Correct 5 ms 4992 KB Output is correct
20 Correct 5 ms 4992 KB Output is correct
21 Correct 5 ms 4992 KB Output is correct
22 Correct 5 ms 4992 KB Output is correct

Subtask #3
29.0 / 29.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 4948 KB Output is correct
2 Correct 5 ms 4992 KB Output is correct
3 Correct 5 ms 4992 KB Output is correct
4 Correct 5 ms 4992 KB Output is correct
5 Correct 5 ms 4992 KB Output is correct
6 Correct 5 ms 4992 KB Output is correct
7 Correct 6 ms 4992 KB Output is correct
8 Correct 5 ms 4992 KB Output is correct
9 Correct 5 ms 4992 KB Output is correct
10 Correct 6 ms 4992 KB Output is correct
11 Correct 5 ms 4992 KB Output is correct
12 Correct 5 ms 4992 KB Output is correct
13 Correct 5 ms 5120 KB Output is correct
14 Correct 5 ms 4992 KB Output is correct
15 Correct 5 ms 4992 KB Output is correct
16 Correct 5 ms 4992 KB Output is correct
17 Correct 5 ms 4992 KB Output is correct
18 Correct 6 ms 4992 KB Output is correct
19 Correct 5 ms 4992 KB Output is correct
20 Correct 5 ms 4992 KB Output is correct
21 Correct 5 ms 4992 KB Output is correct
22 Correct 5 ms 4992 KB Output is correct
23 Correct 8 ms 5376 KB Output is correct
24 Correct 8 ms 5376 KB Output is correct
25 Correct 8 ms 5376 KB Output is correct
26 Correct 12 ms 5632 KB Output is correct
27 Correct 11 ms 5632 KB Output is correct
28 Correct 10 ms 5680 KB Output is correct
29 Correct 11 ms 5632 KB Output is correct
30 Correct 10 ms 5632 KB Output is correct
31 Correct 11 ms 6016 KB Output is correct

Subtask #4
43.0 / 43.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 4948 KB Output is correct
2 Correct 5 ms 4992 KB Output is correct
3 Correct 5 ms 4992 KB Output is correct
4 Correct 5 ms 4992 KB Output is correct
5 Correct 5 ms 4992 KB Output is correct
6 Correct 5 ms 4992 KB Output is correct
7 Correct 6 ms 4992 KB Output is correct
8 Correct 5 ms 4992 KB Output is correct
9 Correct 5 ms 4992 KB Output is correct
10 Correct 6 ms 4992 KB Output is correct
11 Correct 5 ms 4992 KB Output is correct
12 Correct 5 ms 4992 KB Output is correct
13 Correct 5 ms 5120 KB Output is correct
14 Correct 5 ms 4992 KB Output is correct
15 Correct 5 ms 4992 KB Output is correct
16 Correct 5 ms 4992 KB Output is correct
17 Correct 5 ms 4992 KB Output is correct
18 Correct 6 ms 4992 KB Output is correct
19 Correct 5 ms 4992 KB Output is correct
20 Correct 5 ms 4992 KB Output is correct
21 Correct 5 ms 4992 KB Output is correct
22 Correct 5 ms 4992 KB Output is correct
23 Correct 8 ms 5376 KB Output is correct
24 Correct 8 ms 5376 KB Output is correct
25 Correct 8 ms 5376 KB Output is correct
26 Correct 12 ms 5632 KB Output is correct
27 Correct 11 ms 5632 KB Output is correct
28 Correct 10 ms 5680 KB Output is correct
29 Correct 11 ms 5632 KB Output is correct
30 Correct 10 ms 5632 KB Output is correct
31 Correct 11 ms 6016 KB Output is correct
32 Correct 39 ms 8056 KB Output is correct
33 Correct 41 ms 8052 KB Output is correct
34 Correct 44 ms 8104 KB Output is correct
35 Correct 267 ms 17144 KB Output is correct
36 Correct 258 ms 17760 KB Output is correct
37 Correct 255 ms 17760 KB Output is correct
38 Correct 183 ms 18020 KB Output is correct
39 Correct 182 ms 18004 KB Output is correct
40 Correct 221 ms 17868 KB Output is correct
41 Correct 260 ms 21572 KB Output is correct