Submission #1036344

#	Time	Username	Problem	Language	Result	Execution time	Memory
1036344		underwaterkillerwhale	Power Plant (JOI20_power)	C++17	100 / 100	81 ms	28568 KiB

power

#include <bits/stdc++.h>
#define se              second
#define fs              first
#define mp              make_pair
#define pb              push_back
#define ll              long long
#define ii              pair<ll,ll>
#define ld              long double
#define SZ(v)           (int)v.size()
#define ALL(v)          v.begin(), v.end()
#define bit(msk, i)     ((msk >> i) & 1)
#define iter(id, v)     for(auto id : v)
#define rep(i,m,n)      for(int i=(m); i<=(n); i++)
#define reb(i,m,n)      for(int i=(m); i>=(n); i--)
using namespace std;

mt19937_64 rd(chrono :: steady_clock :: now().time_since_epoch().count());
ll Rand(ll l, ll r) { return uniform_int_distribution<ll> (l, r)(rd); }

const int N = 2e5 + 7;
const int Mod = 1e9 + 7;
const int szBL = 240;
const ll  INF = 1e18;
const int BASE = 137;

int n;
vector<int> ke[N];
int dp[N][3];
int a[N];

void dfs (int u, int p ) {
    iter (&v, ke[u]) {
        if (v == p) continue;
        dfs(v, u);
    }
    dp[u][0] = 0;
    {
        int sum = 0;
        iter (&v, ke[u]) {
            if (v == p) continue;
            sum += dp[v][1];
        }
        dp[u][1] = max(a[u], sum - a[u]);
    }
    int sum = 0;
    iter (&v, ke[u]) {
        if (v == p) continue;
        sum += dp[v][1];
        dp[u][2] = max(dp[u][2], max(dp[v][1] + a[u], dp[v][2] - a[u]));
    }
    dp[u][2] = max(dp[u][2], sum - a[u]);
}

void solution (){
    cin >> n;
    rep (i, 1, n - 1) {
        int u, v;
        cin >> u >> v;
        ke[u].push_back(v);
        ke[v].push_back(u);\
    }
    string s;
    cin >> s;
    rep (i, 1, n) {
        a[i] = s[i - 1] - '0';
    }
    dfs(1, 0);
    int res = 0;
    rep (i, 1, n)
    rep (j, 0, 2) res = max(res, dp[i][j]);
    cout << res<<"\n";
}

#define file(name) freopen(name".inp", "r", stdin); \
freopen(name".out", "w", stdout);
/*
*/
int main () {
//    file("c");
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    ll num_Test = 1;
//    cin >> num_Test;
    while(num_Test--)
        solution();
}
/*
no bug challenge +2

*/

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