#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> pi;
typedef long long int ll;
const int MAXN = 202020;
const ll MAX = 2e9;
vector<pi> edge[MAXN];
ll plen[MAXN];
ll dp1[MAXN];
ll dp2[MAXN];
ll dp3[MAXN];
ll dp4[MAXN];
int N;
void dfs(int node,int par){
ll mx2 = -MAX;
ll mx4 = -MAX;
vector<pi> vect3;
int ccnt = 0;
for(auto i : edge[node]){
if(i.first == par) continue;
ccnt++;
plen[i.first] = i.second;
dfs(i.first,node);
dp1[node] += max(dp1[i.first] , dp2[i.first]);
mx2 = max(mx2 , dp1[i.first] + plen[i.first] - max(dp1[i.first],dp2[i.first]));
mx4 = max(mx4 , dp3[i.first] + plen[i.first] - max(dp2[i.first],dp2[i.first]));
vect3.push_back(pi(dp1[i.first] + plen[i.first] - max(dp1[i.first],dp2[i.first]), i.first));
}
sort(vect3.begin(),vect3.end(),greater<pi>());
dp2[node] = dp1[node] + mx2 + plen[node];
dp4[node] = dp1[node] + mx4 + plen[node];
dp3[node] = dp1[node];
if(ccnt > 1){
for(auto i : edge[node]){
if(i.first == par) continue;
int j;
for(j = 0;j<vect3.size();j++){
if(i.first != vect3[j].second) break;
}
dp3[node] = max(dp3[node] , dp1[node] + dp3[i.first] + plen[i.first] - max(dp1[i.first] , dp2[i.first]) + vect3[j].first);
}
}
// printf("%d %lld %lld %lld %lld\n",node,dp1[node],dp2[node],dp3[node],dp4[node]);
}
int main(){
scanf("%d",&N);
for(int i=1;i<N;i++){
int a,b,c;
scanf("%d %d %d",&a,&b,&c);
edge[a].push_back(pi(b,c));
edge[b].push_back(pi(a,c));
}
dfs(1,1);
printf("%lld\n",max(dp1[1],dp3[1]));
return 0;
}
Compilation message
beads.cpp: In function 'void dfs(int, int)':
beads.cpp:42:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(j = 0;j<vect3.size();j++){
~^~~~~~~~~~~~~
beads.cpp: In function 'int main()':
beads.cpp:58:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d",&N);
~~~~~^~~~~~~~~
beads.cpp:61:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d %d %d",&a,&b,&c);
~~~~~^~~~~~~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
8 ms |
5112 KB |
Output is correct |
| 2 |
Correct |
8 ms |
5112 KB |
Output is correct |
| 3 |
Incorrect |
8 ms |
5112 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
8 ms |
5112 KB |
Output is correct |
| 2 |
Correct |
8 ms |
5112 KB |
Output is correct |
| 3 |
Incorrect |
8 ms |
5112 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
8 ms |
5112 KB |
Output is correct |
| 2 |
Correct |
8 ms |
5112 KB |
Output is correct |
| 3 |
Incorrect |
8 ms |
5112 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
8 ms |
5112 KB |
Output is correct |
| 2 |
Correct |
8 ms |
5112 KB |
Output is correct |
| 3 |
Incorrect |
8 ms |
5112 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
