Submission #1123374

#	Time	Username	Problem	Language	Result	Execution time	Memory
1123374		gdragon	Power Plant (JOI20_power)	C++20	100 / 100	104 ms	26308 KiB

power

#include <bits/stdc++.h>
using namespace std;
#define TASK "long"
#define fi first
#define se second
#define ll long long
#define pb push_back
#define ALL(x) (x).begin(), (x).end()
#define GETBIT(mask, i) ((mask) >> (i) & 1)
#define MASK(i) ((1LL) << (i))
#define SZ(x) ((int)(x).size())
#define mp make_pair
#define CNTBIT(mask) __builtin_popcount(mask)
template<class X, class Y> bool maximize(X &x, Y y){ if (x < y) {x = y; return true;} return false;};
template<class X, class Y> bool minimize(X &x, Y y){ if (x > y) {x = y; return true;} return false;};
typedef pair<int, int> ii;
const int N = 2e5 + 5;
const int inf = 1e9 + 7;
const long long INF = (long long)1e18 + 7;
const int mod = 1e9 + 7;
void add(int &x, int y) {x += y; if (x >= mod) x -= mod;}
void sub(int &x, int y) {x -= y; if (x < 0) x += mod;}
int mul(int x, int y) {return 1LL * x * y % mod;}
// -----------------------------------------//
int n;
bool power[N], on[N];
vector<int> adj[N];
void read() {
    cin >> n;
    for(int i = 1; i < n; i++) {
        int u, v; cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    string s; cin >> s;
    for(int i = 1; i <= n; i++) power[i] = s[i - 1] - '0';
}
int dfs1(int u, int p) {
    int res = 0;
    for(int v: adj[u]) if (v != p) {
        res += (dfs1(v, u) > 0);
    }
    if (res == 0) res += on[u];
    return res;
}
void sub1() {
    vector<int> node;
    for(int i = 1; i <= n; i++) if (power[i]) node.push_back(i);
    int m = SZ(node);
    int ans = 0;
    for(int mask = 0; mask < MASK(m); mask++) {
        for(int i = 0; i < m; i++) on[node[i]] = 0;
        for(int i = 0; i < m; i++) if (GETBIT(mask, i)) on[node[i]] = 1;
        int res = 0;
        for(int i = 1; i <= n; i++) if (power[i]) {
            int tmp = dfs1(i, -1);
            if (tmp > 1) --res;
            else if (on[i] && tmp == 1) ++res;
        }
        ans = max(ans, res);
    }
    cout << ans;
}
int dp[N], ans = 0;
// dp[u]: profit in subtree u that there isn't any node have power is parent of others node
void dfs(int u, int p = -1) {
    for(int v: adj[u]) if (v != p) {
        dfs(v, u);
        dp[u] += dp[v];
        if (power[u]) ans = max(ans, dp[v] + 1);
    }
    if (power[u]) {
        --dp[u];
        dp[u] = max(1, dp[u]);
    }
    ans = max(ans, dp[u]);
}
void lastsub() {
    dfs(1, -1);
    cout << ans;
}
void solve() {
    lastsub(); return;
    if (n <= 16) sub1();
    else lastsub();
}
signed main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    if (fopen(TASK".inp", "r")) {
        freopen(TASK".inp", "r", stdin);
        freopen(TASK".out", "w", stdout);
    }
    int test = 1;
    // cin >> test;
    while(test--) {
        read();
        solve();
    }
    return 0;
}

Compilation message (stderr)

power.cpp: In function 'int main()':
power.cpp:90:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   90 |         freopen(TASK".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
power.cpp:91:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   91 |         freopen(TASK".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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