제출 #938862

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
938862		sysia	구슬과 끈 (APIO14_beads)	C++17	0 / 100	0 ms	348 KiB

beads

//Sylwia Sapkowska
#include <bits/stdc++.h>
#pragma GCC optimize("O3", "unroll-loops")
using namespace std;

void __print(int x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << "'" << x << "'";}
void __print(const char *x) {cerr << '"' << x << '"';}
void __print(const string &x) {cerr << '"' << x << '"';}
void __print(bool x) {cerr << (x ? "true" : "false");}

template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ", "; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? ", " : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifdef LOCAL
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif

#define int long long
typedef pair<int, int> T;
const int oo = 1e18, oo2 = 1e9+7, K = 30;
const int mod = 998244353;

void solve(){
    int n; cin >> n;
    vector<vector<T>>g(n+1);
    for (int i = 1; i<n; i++){
        int a, b, c; cin >> a >> b >> c;
        g[a].emplace_back(b, c);
        g[b].emplace_back(a, c);
    }
    vector dp(n+1, vector<int>(2));
    function<void(int, int, int)>dfs = [&](int v, int pa, int cc){
        int s = 0;
        array<int, 2>mx = {-oo, -oo};
        for (auto [x, c]: g[v]){
            if (x == pa) continue;
            dfs(x, v, c);
            s += max(dp[x][0], dp[x][1]);
            int val = dp[x][0] + c - max(dp[x][1], dp[x][0]);
            debug(v, x, val);
            for (int rep = 0; rep < 2; rep++) {
                if (mx[rep] <= val) {
                    swap(mx[rep], val);
                }
            }
        }
        dp[v][1] = max(0ll, cc + s + mx[0]);
        dp[v][0] = s+max(0ll, mx[0] + mx[1]);
        debug(v, dp[v][0], dp[v][1], mx);
        //dp[v][1] = cc+dp[u][0]+c-dp[u][1]+s1
        //dp[v][0] -> musze znalezc dwa o maksymalnym 
    };
    dfs(1, 1, 0);
    cout << dp[1][0] << "\n";
}

int32_t main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    int t = 1;
    //cin >> t;
    while (t--) solve();

    return 0;
}

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