Submission #869980

#	Time	Username	Problem	Language	Result	Execution time	Memory
869980		green_gold_dog	Power Plant (JOI20_power)	C++17	100 / 100	125 ms	35636 KiB

power

//#pragma GCC optimize("Ofast")
//#pragma GCC target("avx,avx2,sse,sse2,sse3,ssse3,sse4,abm,popcnt,mmx")
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef double db;
typedef long double ldb;
typedef complex<double> cd;

constexpr ll INF64 = 9'000'000'000'000'000'000, INF32 = 2'000'000'000, MOD = 1'000'000'007;
constexpr db PI = acos(-1);
constexpr bool IS_FILE = false, IS_TEST_CASES = false;

random_device rd;
mt19937 rnd32(rd());
mt19937_64 rnd64(rd());

template<typename T>
bool assign_max(T& a, T b) {
        if (b > a) {
                a = b;
                return true;
        }
        return false;
}

template<typename T>
bool assign_min(T& a, T b) {
        if (b < a) {
                a = b;
                return true;
        }
        return false;
}

template<typename T>
T square(T a) {
        return a * a;
}

template<>
struct std::hash<pair<ll, ll>> {
        ll operator() (pair<ll, ll> p) const {
                return ((__int128)p.first * MOD + p.second) % INF64;
        }
};

void dfs(ll v, ll p, vector<vector<ll>>& tree, string& s, vector<ll>& dp1, vector<ll>& dp2) {
        ll mdp2 = 0, mdp1 = 0, sdp2 = 0, sdp1 = 0;
        for (auto i : tree[v]) {
                if (i != p) {
                        dfs(i, v, tree, s, dp1, dp2);
                        assign_max(mdp2, dp2[i]);
                        assign_max(mdp1, dp1[i]);
                        sdp1 += dp1[i];
                        sdp2 += dp2[i];
                }
        }
        if (s[v] == '1') {
                assign_max(dp2[v], 1ll);
                assign_max(dp2[v], sdp2 - 1);
                assign_max(dp1[v], mdp2 + 1);
                assign_max(dp1[v], mdp1);
                assign_max(dp1[v], sdp2 - 1);
        } else {
                dp2[v] = sdp2;
                assign_max(dp1[v], mdp1);
                assign_max(dp1[v], sdp2);
        }
}

void solve() {
        ll n;
        cin >> n;
        vector<vector<ll>> tree(n);
        for (ll i = 1; i < n; i++) {
                ll a, b;
                cin >> a >> b;
                a--;
                b--;
                tree[a].push_back(b);
                tree[b].push_back(a);
        }
        string s;
        cin >> s;
        vector<ll> dp1(n, 0), dp2(n, 0);
        dfs(0, 0, tree, s, dp1, dp2);
        cout << dp1[0] << '\n';
}

int main() {
        if (IS_FILE) {
                freopen("", "r", stdin);
                freopen("", "w", stdout);
        }
        ios_base::sync_with_stdio(false);
        cin.tie(0);
        cout.tie(0);
        ll t = 1;
        if (IS_TEST_CASES) {
                cin >> t;
        }
        for (ll i = 0; i < t; i++) {
                solve();
        }
}

Compilation message (stderr)

power.cpp: In function 'int main()':
power.cpp:95:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   95 |                 freopen("", "r", stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~
power.cpp:96:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   96 |                 freopen("", "w", stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 6 / 6
• Subtask 2: 41 / 41
• Subtask 3: 53 / 53