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Submission #734423

# Submission time Handle Problem Language Result Execution time Memory
734423 2023-05-02T11:36:34 Z Alihan_8 Beads and wires (APIO14_beads) C++17
100 / 100
 358 ms 51016 KB 
#include <bits/stdc++.h>

using namespace std;

#define all(x) x.begin(), x.end()
#define pb push_back
#define ln '\n'
#define int long long

template <class _T>
bool chmin(_T &x, const _T &y){
    bool flag = false;
    if ( x > y ){
        x = y; flag |= true;
    }
    return flag;
}

template <class _T>
bool chmax(_T &x, const _T &y){
    bool flag = false;
    if ( x < y ){
        x = y; flag |= true;
    }
    return flag;
}

signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int n; cin >> n;
    vector <pair<int,int>> g[n];
    for ( int i = 1; i < n; i++ ){
        int x, y, w; cin >> x >> y >> w;
        g[--x].pb({--y, w});
        g[y].pb({x, w});
    }
    const int inf = 1e18 + 1;
    vector <array<int,2>> dp(n);
    multiset <int> s[n];
    vector <int> par_w(n);
    function <void(int,int,int)> dfs = [&](int x, int par, int prev){
        int cnt = 0;
        par_w[x] = prev;
        for ( auto [to, w]: g[x] ){
            if ( to == par ) continue;
            dfs(to, x, w);
            cnt += dp[to][1];
            s[x].insert(dp[to][0] - dp[to][1] + w);

        }
        dp[x][0] = cnt;
        if ( !s[x].empty() ){
            dp[x][1] = cnt + *s[x].rbegin() + par_w[x];
        }
        chmax(dp[x][1], dp[x][0]);
    };
    int res = 0;
    function <void(int,int)> reRoot = [&](int x, int par){
        chmax(res, dp[x][0]);
        auto erase = [&](int x, int val){
            s[x].erase(s[x].find(val));
        };
        for ( auto [to, w]: g[x] ){
            if ( to == par ) continue;
            par_w[x] = w; par_w[to] = 0;
            erase(x, -dp[to][1] + dp[to][0] + w);
            dp[x][0] -= dp[to][1];
            dp[x][1] = dp[x][0];
            if ( !s[x].empty() ){
                chmax(dp[x][1], dp[x][0] + *s[x].rbegin() + par_w[x]);
            }
            s[to].insert(dp[x][0] + w - dp[x][1]);
            dp[to][0] += dp[x][1];
            dp[to][1] = max(dp[to][0], dp[to][0] + *s[to].rbegin() + par_w[to]);
            reRoot(to, x);
            swap(x, to);
            par_w[x] = w; par_w[to] = 0;
            erase(x, -dp[to][1] + dp[to][0] + w);
            dp[x][0] -= dp[to][1];
            dp[x][1] = dp[x][0];
            if ( !s[x].empty() ){
                chmax(dp[x][1], dp[x][0] + *s[x].rbegin() + par_w[x]);
            }
            s[to].insert(dp[x][0] + w - dp[x][1]);
            dp[to][0] += dp[x][1];
            dp[to][1] = max(dp[to][0], dp[to][0] + *s[to].rbegin() + par_w[to]);
            swap(x, to);
        }
    };
    dfs(0, -1, 0);
    reRoot(0, -1);
    cout << res;

    cout << '\n';
}
/*
10
4 10 2
1 2 21
1 3 13
6 7 1
7 9 5
2 4 3
2 5 8
1 6 55
6 8 34
*/

Compilation message

beads.cpp: In function 'int main()':
beads.cpp:39:15: warning: unused variable 'inf' [-Wunused-variable]
   39 |     const int inf = 1e18 + 1;
      |               ^~~

Subtask #1
13.0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 1 ms 212 KB Output is correct
3 Correct 1 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 0 ms 320 KB Output is correct
6 Correct 1 ms 212 KB Output is correct
7 Correct 1 ms 212 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 1 ms 212 KB Output is correct
10 Correct 1 ms 212 KB Output is correct
11 Correct 1 ms 212 KB Output is correct
12 Correct 1 ms 212 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 1 ms 212 KB Output is correct
3 Correct 1 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 0 ms 320 KB Output is correct
6 Correct 1 ms 212 KB Output is correct
7 Correct 1 ms 212 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 1 ms 212 KB Output is correct
10 Correct 1 ms 212 KB Output is correct
11 Correct 1 ms 212 KB Output is correct
12 Correct 1 ms 212 KB Output is correct
13 Correct 1 ms 212 KB Output is correct
14 Correct 1 ms 320 KB Output is correct
15 Correct 1 ms 212 KB Output is correct
16 Correct 1 ms 340 KB Output is correct
17 Correct 1 ms 340 KB Output is correct
18 Correct 1 ms 340 KB Output is correct
19 Correct 1 ms 340 KB Output is correct
20 Correct 1 ms 340 KB Output is correct
21 Correct 1 ms 340 KB Output is correct
22 Correct 1 ms 320 KB Output is correct

Subtask #3
29.0 / 29.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 1 ms 212 KB Output is correct
3 Correct 1 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 0 ms 320 KB Output is correct
6 Correct 1 ms 212 KB Output is correct
7 Correct 1 ms 212 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 1 ms 212 KB Output is correct
10 Correct 1 ms 212 KB Output is correct
11 Correct 1 ms 212 KB Output is correct
12 Correct 1 ms 212 KB Output is correct
13 Correct 1 ms 212 KB Output is correct
14 Correct 1 ms 320 KB Output is correct
15 Correct 1 ms 212 KB Output is correct
16 Correct 1 ms 340 KB Output is correct
17 Correct 1 ms 340 KB Output is correct
18 Correct 1 ms 340 KB Output is correct
19 Correct 1 ms 340 KB Output is correct
20 Correct 1 ms 340 KB Output is correct
21 Correct 1 ms 340 KB Output is correct
22 Correct 1 ms 320 KB Output is correct
23 Correct 5 ms 1236 KB Output is correct
24 Correct 5 ms 1300 KB Output is correct
25 Correct 5 ms 1364 KB Output is correct
26 Correct 8 ms 2388 KB Output is correct
27 Correct 8 ms 2388 KB Output is correct
28 Correct 10 ms 2392 KB Output is correct
29 Correct 10 ms 2252 KB Output is correct
30 Correct 9 ms 2252 KB Output is correct
31 Correct 10 ms 3156 KB Output is correct

Subtask #4
43.0 / 43.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 1 ms 212 KB Output is correct
3 Correct 1 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 0 ms 320 KB Output is correct
6 Correct 1 ms 212 KB Output is correct
7 Correct 1 ms 212 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 1 ms 212 KB Output is correct
10 Correct 1 ms 212 KB Output is correct
11 Correct 1 ms 212 KB Output is correct
12 Correct 1 ms 212 KB Output is correct
13 Correct 1 ms 212 KB Output is correct
14 Correct 1 ms 320 KB Output is correct
15 Correct 1 ms 212 KB Output is correct
16 Correct 1 ms 340 KB Output is correct
17 Correct 1 ms 340 KB Output is correct
18 Correct 1 ms 340 KB Output is correct
19 Correct 1 ms 340 KB Output is correct
20 Correct 1 ms 340 KB Output is correct
21 Correct 1 ms 340 KB Output is correct
22 Correct 1 ms 320 KB Output is correct
23 Correct 5 ms 1236 KB Output is correct
24 Correct 5 ms 1300 KB Output is correct
25 Correct 5 ms 1364 KB Output is correct
26 Correct 8 ms 2388 KB Output is correct
27 Correct 8 ms 2388 KB Output is correct
28 Correct 10 ms 2392 KB Output is correct
29 Correct 10 ms 2252 KB Output is correct
30 Correct 9 ms 2252 KB Output is correct
31 Correct 10 ms 3156 KB Output is correct
32 Correct 46 ms 10572 KB Output is correct
33 Correct 60 ms 10572 KB Output is correct
34 Correct 47 ms 10612 KB Output is correct
35 Correct 334 ms 42376 KB Output is correct
36 Correct 278 ms 42184 KB Output is correct
37 Correct 298 ms 42392 KB Output is correct
38 Correct 358 ms 41576 KB Output is correct
39 Correct 342 ms 41456 KB Output is correct
40 Correct 342 ms 41400 KB Output is correct
41 Correct 319 ms 51016 KB Output is correct