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Submission #161649

# Submission time Handle Problem Language Result Execution time Memory
161649 2019-11-03T12:15:03 Z arnold518 Beads and wires (APIO14_beads) C++14
0 / 100
 6 ms 5240 KB 
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int MAXN = 2e5;
const ll INF = 1e15;

int N;
vector<pii> adj[MAXN+10];
ll dp1[MAXN+10], dp2[MAXN+10], dp3[MAXN+10], dp4[MAXN+10], len[MAXN+10], ans;

void dfs(int now, int bef, ll par)
{
    ll val=0;
    len[now]=par;
    for(pii nxt : adj[now])
    {
        if(nxt.first==bef) continue;
        dfs(nxt.first, now, nxt.second);
        dp2[now]+=dp1[nxt.first];
        val=max(val, par-dp1[nxt.first]+dp2[nxt.first]+nxt.second);
    }
    dp1[now]=dp2[now]+val;
    //printf("%d %lld %lld\n", now, dp1[now], dp2[now]);
}

void dfs2(int now, int bef)
{
    ll val=0;
    dp4[now]=dp2[bef]-dp1[now]+dp3[bef];
    for(pii nxt : adj[bef])
    {
        if(nxt.first==now) continue;
        val=max(val, -dp1[nxt.first]+dp2[nxt.first]+len[nxt.first]+len[now]);
    }
    dp3[now]=dp2[bef]-dp1[now]+dp3[bef]+val;
    dp3[now]=max(dp3[now], dp2[bef]-dp1[now]+dp4[bef]+len[now]+len[bef]);
    if(now==1) dp3[now]=dp4[now]=0;
    for(pii nxt : adj[now])
    {
        if(nxt.first==bef) continue;
        dfs2(nxt.first, now);
    }
}

int main()
{
    int i, j;

    scanf("%d", &N);
    for(i=1; i<N; i++)
    {
        int u, v, w;
        scanf("%d%d%d", &u, &v, &w);
        adj[u].push_back({v, w});
        adj[v].push_back({u, w});
    }

    dfs(1, 0, -INF);
    dfs2(1, 0);

    for(i=1; i<=N; i++) ans=max(ans, dp2[i]+dp3[i]);
    printf("%lld", ans);
}

Compilation message

beads.cpp: In function 'int main()':
beads.cpp:51:12: warning: unused variable 'j' [-Wunused-variable]
     int i, j;
            ^
beads.cpp:53:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &N);
     ~~~~~^~~~~~~~~~
beads.cpp:57:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d%d", &u, &v, &w);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~

Subtask #1
0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 4984 KB Output is correct
2 Correct 6 ms 5112 KB Output is correct
3 Correct 6 ms 5240 KB Output is correct
4 Correct 6 ms 4984 KB Output is correct
5 Incorrect 6 ms 4984 KB Output isn't correct
6 Halted 0 ms 0 KB -

Subtask #2
0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 4984 KB Output is correct
2 Correct 6 ms 5112 KB Output is correct
3 Correct 6 ms 5240 KB Output is correct
4 Correct 6 ms 4984 KB Output is correct
5 Incorrect 6 ms 4984 KB Output isn't correct
6 Halted 0 ms 0 KB -

Subtask #3
0 / 29.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 4984 KB Output is correct
2 Correct 6 ms 5112 KB Output is correct
3 Correct 6 ms 5240 KB Output is correct
4 Correct 6 ms 4984 KB Output is correct
5 Incorrect 6 ms 4984 KB Output isn't correct
6 Halted 0 ms 0 KB -

Subtask #4
0 / 43.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 4984 KB Output is correct
2 Correct 6 ms 5112 KB Output is correct
3 Correct 6 ms 5240 KB Output is correct
4 Correct 6 ms 4984 KB Output is correct
5 Incorrect 6 ms 4984 KB Output isn't correct
6 Halted 0 ms 0 KB -