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Submission #161663

# Submission time Handle Problem Language Result Execution time Memory
161663 2019-11-03T13:50:53 Z arnold518 Beads and wires (APIO14_beads) C++14
100 / 100
 315 ms 32736 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;
}

void dfs2(int now, int bef, vector<pll> &V)
{
    int i, j;
    vector<pll> V2;
    for(pii nxt : adj[now])
    {
        if(nxt.first==bef) continue;
        V2.push_back({-dp1[nxt.first]+dp2[nxt.first]+len[nxt.first], nxt.first});
    }
    sort(V2.begin(), V2.end(), greater<pll>());

    if(now==1) dp3[now]=dp4[now]=0;
    else
    {
        dp3[now]=dp4[now]=dp2[bef]-dp1[now]+dp3[bef];

        ll val=-INF;
        for(i=0; i<2 && i<V.size(); i++)
        {
            if(V[i].second!=now)
            {
                val=max(val, V[i].first);
                break;
            }
        }
        dp3[now]=max(dp3[now], dp2[bef]-dp1[now]+len[now]+dp3[bef]+val);
        if(bef!=1) dp3[now]=max(dp3[now], dp2[bef]-dp1[now]+len[now]+len[bef]+dp4[bef]);
    }

    //printf("%d %lld %lld %lld %lld\n", now, dp1[now], dp2[now], dp3[now], dp4[now]);

    for(pii nxt : adj[now])
    {
        if(nxt.first==bef) continue;
        dfs2(nxt.first, now, V2);
    }
}

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, 1, -INF);

    vector<pll> T;
    dfs2(1, 1, T);

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

Compilation message

beads.cpp: In function 'void dfs2(int, int, std::vector<std::pair<long long int, long long int> >&)':
beads.cpp:46:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(i=0; i<2 && i<V.size(); i++)
                         ~^~~~~~~~~
beads.cpp:31:12: warning: unused variable 'j' [-Wunused-variable]
     int i, j;
            ^
beads.cpp: In function 'int main()':
beads.cpp:69:12: warning: unused variable 'j' [-Wunused-variable]
     int i, j;
            ^
beads.cpp:71:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &N);
     ~~~~~^~~~~~~~~~
beads.cpp:75:14: 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
13.0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 4984 KB Output is correct
2 Correct 6 ms 4984 KB Output is correct
3 Correct 7 ms 5116 KB Output is correct
4 Correct 6 ms 4984 KB Output is correct
5 Correct 6 ms 4856 KB Output is correct
6 Correct 6 ms 5084 KB Output is correct
7 Correct 6 ms 4984 KB Output is correct
8 Correct 6 ms 4984 KB Output is correct
9 Correct 7 ms 5112 KB Output is correct
10 Correct 6 ms 4984 KB Output is correct
11 Correct 6 ms 4984 KB Output is correct
12 Correct 7 ms 4984 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 4984 KB Output is correct
2 Correct 6 ms 4984 KB Output is correct
3 Correct 7 ms 5116 KB Output is correct
4 Correct 6 ms 4984 KB Output is correct
5 Correct 6 ms 4856 KB Output is correct
6 Correct 6 ms 5084 KB Output is correct
7 Correct 6 ms 4984 KB Output is correct
8 Correct 6 ms 4984 KB Output is correct
9 Correct 7 ms 5112 KB Output is correct
10 Correct 6 ms 4984 KB Output is correct
11 Correct 6 ms 4984 KB Output is correct
12 Correct 7 ms 4984 KB Output is correct
13 Correct 7 ms 4988 KB Output is correct
14 Correct 7 ms 5088 KB Output is correct
15 Correct 6 ms 4984 KB Output is correct
16 Correct 7 ms 4984 KB Output is correct
17 Correct 6 ms 4984 KB Output is correct
18 Correct 6 ms 4984 KB Output is correct
19 Correct 6 ms 5116 KB Output is correct
20 Correct 6 ms 5112 KB Output is correct
21 Correct 6 ms 4984 KB Output is correct
22 Correct 7 ms 5112 KB Output is correct

Subtask #3
29.0 / 29.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 4984 KB Output is correct
2 Correct 6 ms 4984 KB Output is correct
3 Correct 7 ms 5116 KB Output is correct
4 Correct 6 ms 4984 KB Output is correct
5 Correct 6 ms 4856 KB Output is correct
6 Correct 6 ms 5084 KB Output is correct
7 Correct 6 ms 4984 KB Output is correct
8 Correct 6 ms 4984 KB Output is correct
9 Correct 7 ms 5112 KB Output is correct
10 Correct 6 ms 4984 KB Output is correct
11 Correct 6 ms 4984 KB Output is correct
12 Correct 7 ms 4984 KB Output is correct
13 Correct 7 ms 4988 KB Output is correct
14 Correct 7 ms 5088 KB Output is correct
15 Correct 6 ms 4984 KB Output is correct
16 Correct 7 ms 4984 KB Output is correct
17 Correct 6 ms 4984 KB Output is correct
18 Correct 6 ms 4984 KB Output is correct
19 Correct 6 ms 5116 KB Output is correct
20 Correct 6 ms 5112 KB Output is correct
21 Correct 6 ms 4984 KB Output is correct
22 Correct 7 ms 5112 KB Output is correct
23 Correct 10 ms 5496 KB Output is correct
24 Correct 10 ms 5496 KB Output is correct
25 Correct 10 ms 5496 KB Output is correct
26 Correct 14 ms 5880 KB Output is correct
27 Correct 14 ms 6008 KB Output is correct
28 Correct 13 ms 6392 KB Output is correct
29 Correct 25 ms 6136 KB Output is correct
30 Correct 13 ms 6136 KB Output is correct
31 Correct 14 ms 6776 KB Output is correct

Subtask #4
43.0 / 43.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 4984 KB Output is correct
2 Correct 6 ms 4984 KB Output is correct
3 Correct 7 ms 5116 KB Output is correct
4 Correct 6 ms 4984 KB Output is correct
5 Correct 6 ms 4856 KB Output is correct
6 Correct 6 ms 5084 KB Output is correct
7 Correct 6 ms 4984 KB Output is correct
8 Correct 6 ms 4984 KB Output is correct
9 Correct 7 ms 5112 KB Output is correct
10 Correct 6 ms 4984 KB Output is correct
11 Correct 6 ms 4984 KB Output is correct
12 Correct 7 ms 4984 KB Output is correct
13 Correct 7 ms 4988 KB Output is correct
14 Correct 7 ms 5088 KB Output is correct
15 Correct 6 ms 4984 KB Output is correct
16 Correct 7 ms 4984 KB Output is correct
17 Correct 6 ms 4984 KB Output is correct
18 Correct 6 ms 4984 KB Output is correct
19 Correct 6 ms 5116 KB Output is correct
20 Correct 6 ms 5112 KB Output is correct
21 Correct 6 ms 4984 KB Output is correct
22 Correct 7 ms 5112 KB Output is correct
23 Correct 10 ms 5496 KB Output is correct
24 Correct 10 ms 5496 KB Output is correct
25 Correct 10 ms 5496 KB Output is correct
26 Correct 14 ms 5880 KB Output is correct
27 Correct 14 ms 6008 KB Output is correct
28 Correct 13 ms 6392 KB Output is correct
29 Correct 25 ms 6136 KB Output is correct
30 Correct 13 ms 6136 KB Output is correct
31 Correct 14 ms 6776 KB Output is correct
32 Correct 49 ms 9664 KB Output is correct
33 Correct 56 ms 9720 KB Output is correct
34 Correct 51 ms 9720 KB Output is correct
35 Correct 312 ms 24048 KB Output is correct
36 Correct 310 ms 23908 KB Output is correct
37 Correct 315 ms 23872 KB Output is correct
38 Correct 220 ms 27248 KB Output is correct
39 Correct 213 ms 27232 KB Output is correct
40 Correct 237 ms 27612 KB Output is correct
41 Correct 299 ms 32736 KB Output is correct