Submission #122571

#	Time	Username	Problem	Language	Result	Execution time	Memory
122571		popovicirobert	Triumphal arch (POI13_luk)	C++14	0 / 100	1571 ms	28636 KiB

luk

#include <bits/stdc++.h>
#define lsb(x) (x & (-x))
#define ll long long
#define ull unsigned long long
// 217
// 44

/*
const int MOD = ;

inline void mod(int &x) {
    if(x >= MOD)
        x -= MOD;
}

inline void add(int &x, int y) {
    x += y;
    mod(x);
}

inline void sub(int &x, int y) {
    x += MOD - y;
    mod(x);
}


inline void mul(int &x, int y) {
    x = (1LL * x * y) % MOD;
}
*/

using namespace std;

const ll INF = 1e18;
const int MAXN = (int) 3e5;

vector <int> g[MAXN + 1];
int deg[MAXN + 1];
bool leaf[MAXN + 1];

ll vals[MAXN + 1];
ll dp[MAXN + 1][2];
// dp[nod][0] = drumul max pe care te termini daca nu ai revenit in nod
// dp[nod][1] = drumul max pe care te termini daca revi in nod

void dfs(int nod, int par, int delta) {
    int son = 0;
    for(auto it : g[nod]) {
        if(it != par && leaf[it] == 0) {
            dfs(it, nod, delta);
            son++;
        }
    }

    dp[nod][0] = dp[nod][1] = -INF;
    if(son == 0) {
        dp[nod][0] = vals[nod] - delta;
        dp[nod][1] = vals[nod] - 2 * delta;
        return ;
    }

    vector <ll> aux(2);
    aux[0] = vals[nod] - delta;
    aux[1] = 0;

    for(auto it : g[nod]) {
        if(it == par || leaf[it]) {
            continue;
        }
        vector <ll> cur(2, -INF);
        cur[0] = max(aux[0], max(aux[0] + dp[it][1] - delta, aux[1] + dp[it][0]));
        cur[1] = max(aux[1], aux[1] + dp[it][1] - delta);
        swap(cur, aux);
    }

    aux[1] = max(aux[1] + vals[nod] - delta, vals[nod] - 2 * delta);

    for(int i = 0; i < 2; i++) {
        dp[nod][i] = aux[i];
    }
}

inline ll check(int delta) {
    dfs(1, 0, delta);
    return max(dp[1][0], dp[1][1]);
}


int main() {
    //ifstream cin("A.in");
    //ofstream cout("A.out");
    int i, n;
    ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);

    cin >> n;

    for(i = 1; i < n; i++) {
        int x, y;
        cin >> x >> y;
        g[x].push_back(y);
        g[y].push_back(x);
        deg[x]++, deg[y]++;
    }

    for(i = 1; i <= n; i++) {
        if(deg[i] == 1 && i != 1) {
            leaf[i] = 1;
        }
        vals[i] = deg[i] - (i != 1);
    }

    int res = -1;
    for(int step = 1 << 18; step; step >>= 1) {
        if(check(res + step) > 0) {
            res += step;
        }
    }

    cout << res + 1;

    //cin.close();
    //cout.close();
    return 0;
}

• Subtask 1: 0 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 10
• Subtask 4: 0 / 10
• Subtask 5: 0 / 10
• Subtask 6: 0 / 10
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10
• Subtask 10: 0 / 10