Submission #59741

#	Time	Username	Problem	Language	Result	Execution time	Memory
59741		Benq	구슬과 끈 (APIO14_beads)	C++11	28 / 100	1079 ms	1024 KiB

beads

#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
 
using namespace std;
using namespace __gnu_pbds;
 
typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;
 
typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef pair<ld,ld> pd;
 
typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<cd> vcd;
 
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;
 
#define FOR(i, a, b) for (int i=a; i<(b); i++)
#define F0R(i, a) for (int i=0; i<(a); i++)
#define FORd(i,a,b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)
 
#define sz(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()
 
const int MOD = 1000000007;
const ll INF = 1e18;
const int MX = 10001;

int n;
vpi adj[MX];

pi comb(pi ret, pi x, int len) {
    ret.s = max(ret.s+max(x.f,x.s),ret.f+len+x.f);
    ret.f += max(x.f,x.s);
    return ret;
}

pi dfs(int cur, int pre) {
    pi ret = {0,-MOD}; // no needed, needed
    for (auto a: adj[cur]) if (a.f != pre) {
        pi x = dfs(a.f,cur); x.s += a.s;
        ret = comb(ret,x,a.s);
    }
    // cout << cur << " " << ret.f << " " << ret.s << "\n";
    return ret;
}

int main() {
    ios_base::sync_with_stdio(0); cin.tie(0);
    cin >> n;
    F0R(i,n-1) {
        int a,b,c; cin >> a >> b >> c;
        adj[a].pb({b,c}), adj[b].pb({a,c});
    }
    int ans = 0;
    // dfs(5,0);
    FOR(i,1,n+1) {
        // cout << dfs(i,0).f << "\n";
        ans = max(ans,dfs(i,0).f);
    }
    cout << ans;
}
 
/* Look for:
* the exact constraints (multiple sets are too slow for n=10^6 :( ) 
* special cases (n=1?)
* overflow (ll vs int?)
* array bounds
*/

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