Submission #36911

#	Time	Username	Problem	Language	Result	Execution time	Memory
36911		mohammad_kilani	Beads and wires (APIO14_beads)	C++14	28 / 100	1082 ms	5632 KiB

beads

#include <bits/stdc++.h>
using namespace std;
#define mod 1000000007
#define oo 2000000000
const int N = 200010;
vector< pair<int,int> > g[N];
int n , dp[N][2] , q[N], in[N];

int main() {
	//freopen("in.txt","r",stdin);
	scanf("%d",&n);
	for(int i=0;i<n-1;i++){
		int u ,v , w;
		scanf("%d%d%d",&u,&v,&w);
		g[u].push_back(make_pair(v,w));
		g[v].push_back(make_pair(u,w));
	}
	int ans = 0 , st = 0 , en = 0 , curnode , w , sum = 0 , mx = 0;
	for(int node=1;node<=n;node++){
		if(g[node].size() == 1){
			st = 0 , en = 0 ,sum = 0;
			for(int i=1;i<=n;i++){
				in[i] = g[i].size() - (i != node);
				if(in[i] == 0)
					q[en++] = i;
			}
			while(st < en){
				curnode = q[st++];
				dp[curnode][1] = dp[curnode][0] = 0;
				sum = 0 , mx = -oo;
				for(int i=0;i<g[curnode].size();i++){
					if(in[g[curnode][i].first] != 0){
						w = g[curnode][i].second;
						in[g[curnode][i].first]--;
						if(in[g[curnode][i].first] == 0){
							q[en++] = g[curnode][i].first;
						}
					}
					else{
						sum += max(dp[g[curnode][i].first][0],dp[g[curnode][i].first][1]);
						mx = max(mx,dp[g[curnode][i].first][1] + g[curnode][i].second - max(dp[g[curnode][i].first][0],dp[g[curnode][i].first][1]));
					}
				}
				dp[curnode][1] = sum;
				dp[curnode][0] = sum + mx + w;

			}
			ans = max(ans,dp[node][1]);
		}
	}
	printf("%d\n",ans);
	return 0;
}

Compilation message (stderr)

beads.cpp: In function 'int main()':
beads.cpp:31:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<g[curnode].size();i++){
                 ~^~~~~~~~~~~~~~~~~~
beads.cpp:11:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ~~~~~^~~~~~~~~
beads.cpp:14:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d%d",&u,&v,&w);
   ~~~~~^~~~~~~~~~~~~~~~~~~
beads.cpp:45:31: warning: 'w' may be used uninitialized in this function [-Wmaybe-uninitialized]
     dp[curnode][0] = sum + mx + w;
                      ~~~~~~~~~^~~

• Subtask 1: 13 / 13
• Subtask 2: 15 / 15
• Subtask 3: 0 / 29
• Subtask 4: 0 / 43