Submission #720915

#	Time	Username	Problem	Language	Result	Execution time	Memory
720915		TB_	Beads and wires (APIO14_beads)	C++14	28 / 100	1081 ms	31316 KiB

beads

#include <bits/stdc++.h>
using namespace std;

// #undef _GLIBCXX_DEBUG                // disable run-time bound checking, etc
// #pragma GCC optimize("Ofast,inline") // Ofast = O3,fast-math,allow-store-data-races,no-protect-parens
// #pragma GCC optimize ("unroll-loops")

// #pragma GCC target("bmi,bmi2,lzcnt,popcnt")                      // bit manipulation
// #pragma GCC target("movbe")                                      // byte swap
// #pragma GCC target("aes,pclmul,rdrnd")                           // encryption
// #pragma GCC target("avx,avx2,f16c,fma,sse3,ssse3,sse4.1,sse4.2") // SIMD

// #include <bits/extc++.h>
// using namespace __gnu_pbds;
// template<class T>using ordered_set = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;
// template<class T>using ordered_multiset = tree<T, null_type, less_equal<T>, rb_tree_tag,tree_order_statistics_node_update>;

#define ll long long
#define INF (ll)1e9+7
#define fo(i, n) for(int i=0;i<(int)n;i++)
#define Fo(i, k, n) for(i=k;k<n?i<n:i>n;k<n?i+=1:i-=1)
#define deb(x) cout << #x << " = " << x << endl;
#define deb2(x, y) cout << #x << " = " << x << ", " << #y << " = " << y << endl
#define pb push_back
#define mp make_pair
#define F first
#define S second
#define LSOne(S) ((S) & (-S))
#define sp(x, y) fixed<<setprecision(y)<<x
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define clr(x) memset(x, 0, sizeof(x))
#define tr(it, x) for(auto it = x.begin(); it != x.end(); it++)
#define trr(it, x) for(auto it = x.rbegin(); it != x.rend(); it+)
inline int readint(){ int v = 0; char c; while((c = getchar()) != EOF && c != ' ' && c != '\n'){ v *= 10; v += c - '0'; } return v; }
inline int readintsigned() { int v = 0; int sign = 1; char c = getchar(); if (c == '-') { sign = -1; } else { v += c - '0'; } while ((c = getchar()) != EOF && c != ' ' && c != '\n') { v *= 10; v += c - '0'; } return v * sign; }
inline string readstring() { string s; char c; while ((c = getchar()) != EOF && c != '\n' && c != ' ') { s.push_back(c); } return s; }
template <class result_t=std::chrono::milliseconds,class clock_t=std::chrono::steady_clock,class duration_t = std::chrono::milliseconds>
auto since(std::chrono::time_point<clock_t, duration_t> const& start){return std::chrono::duration_cast<result_t>(clock_t::now() - start);}
typedef pair<int, int> pii;
typedef pair<ll, ll> pl;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<pii> vpii;
typedef vector<pl> vpl;
typedef vector<vi> vvi;
typedef vector<vl> vvl;
typedef vector<vpii> vvpii;
typedef vector<vpl> vvpl;

vvpl adj(200001);
unordered_map<ll, ll> memo[200001][2];

ll dp2(int pos, int last);

ll dp(int pos, int last){
    if(memo[pos][0].count(last)) return memo[pos][0][last];
    ll ans = 0;
    for(auto v : adj[pos]){
        if(v.F == last) continue;
        ll val = max(dp(v.F, pos), dp2(v.F, pos)+v.S);
        ans += val;
        // biggest.pb(dp(v.F, pos)+v.S-val);
    }
    memo[pos][0][last] = ans;
    return ans;
}

ll dp2(int pos, int last){
    if(memo[pos][1].count(last)) return memo[pos][1][last];
    ll ans = 0;
    ll biggest = -INF;
    for(auto v : adj[pos]){
        if(v.F == last) continue;
        ll val = max(dp2(v.F, pos)+v.S, dp(v.F, pos));
        ans += val;
        biggest = max(biggest, dp(v.F, pos)+v.S-val);
    }
    ans+=biggest;
    // deb2(pos, ans);
    memo[pos][1][last] = ans;
    return ans;
}
int main() {
    // cout << fixed << setprecision(20);
    // auto start = std::chrono::steady_clock::now(); // since(start).count()
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit); // remove if to endof file

    int n, from, to, weight;
    cin >> n;
    fo(i, n-1){
        cin >> from >> to >> weight;
        adj[--from].pb(mp(--to, weight));
        adj[to].pb(mp(from, weight));
    }
    ll res = 0;
    fo(i, n) res = max(res, dp(i, i));
    cout << res;
    // fo(i, n){

    //     memset(memo, -1, sizeof(memo));
    //     // cout << dp(0, 0);
    //     deb2(i, dp(i, i));
    // }


    return 0;
}

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