Submission #1049033

#	Time	Username	Problem	Language	Result	Execution time	Memory
1049033		crafticat	Power Plant (JOI20_power)	C++17	47 / 100	1556 ms	16088 KiB

power

#include <bits/stdc++.h>

using namespace std;

#include <bits/stdc++.h>

#include <utility>

using namespace std;

using ll = long long;
using pi = pair<int,int>;
using pl = pair<ll,ll>;

#define temp(T) template<class T>
temp(T) using V = vector<T>;
using vi = V<int>;
using vl = V<ll>;
using vvi = V<vi>;
using vpi = V<pi>;
using vb = V<bool>;
using vvb = V<vb>;
vi dx = {0,1,-1,0};
vi dy = {1,0,0,-1};

#define sz(x) x.size()
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
#define sor(x) sort(all(x))
#define rsz resize
#define ins insert
#define pb push_back
#define eb emplace_back
#define f first
#define s second

#define lb lower_bound
#define ub upper_bound

#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define rep(a) F0R(_,a)
#define each(a,x) for (auto& a: x)

using str = string;

const int MOD = 1e9 + 7;
const ll BIG = 1e18;
const int INF = 1e9 + 2;

temp(T) bool ckmin(T& a, const T& b) {
    return b < a ? a = b, 1 : 0; } // set a = min(a,b)
temp(T) bool ckmax(T& a, const T& b) {
    return a < b ? a = b, 1 : 0; } // set a = max(a,b)

void unsyncIO() { cin.tie(0)->sync_with_stdio(0); }
// FILE I/O
void setIn(str s) { freopen(s.c_str(),"r",stdin); }
void setOut(str s) { freopen(s.c_str(),"w",stdout); }
void setIO(str s = "") {
    unsyncIO();
    if (sz(s)) setIn(s+".in"), setOut(s+".out"); // for USACO
}

#define read(x) int x; cin >> x

temp(T) void pr(T x) {
    cout << to_string(x);
}
temp(T) void prln(T x) {
    cout << to_string(x) << "\n";
}


vi readV(int n) {
    vi input(n);
    F0R(i,n)
        cin >> input[i];
    return input;
}

vi dp2;
vi up;
vvi g;
string active;

void dfs(int x, int p) {
    each(y, g[x]) {
        if (y == p) continue;
        dfs(y, x);
        if (active[y] == '1') dp2[x] += 1;
        else dp2[x] += dp2[y];
    }
}

void dfs2(int x, int p) {
    if (p != -1) {
        if (active[p] == '1') up[x] = 1;
        else up[x] = dp2[p] - (active[x] == '1' ? 1 : dp2[x]) + up[x];
    }

    each(y, g[x]) {
        if (y == p) continue;
        dfs2(y, x);
    }
}
int test(int x, int p) {
    int ans = 0;
    each(y, g[x]) {
        if (y == p) continue;
        int cs = test(y, x);
        if (active[y] == '1') { cs--; if (cs < 1) cs = 1;}
        ans += cs;
    }
    return ans;
}

int main() {
    setIO();

    read(n);

    g.rsz(n + 1);
    F0R(i, n -1) {
        int a, b; cin >> a >> b;
        g[a].pb(b);
        g[b].pb(a);
    }

    cin >> active;
    active = " " + active;
    dp2.rsz(n + 1);
    up.rsz(n + 1);

    dfs(1, -1);
    dfs2(1, -1);

    int ans =0;
    FOR(i, 1, n + 1) {
        int sum = test(i, -1);
        if (active[i] == '1' and sum > 2) sum--;
        if (active[i] == '1' and sum == 0) sum = 1;
        ckmax(ans, sum);
    }

    cout << ans;

    return 0;
}

Compilation message (stderr)

power.cpp: In function 'void setIn(str)':
power.cpp:60:28: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   60 | void setIn(str s) { freopen(s.c_str(),"r",stdin); }
      |                     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
power.cpp: In function 'void setOut(str)':
power.cpp:61:29: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   61 | void setOut(str s) { freopen(s.c_str(),"w",stdout); }
      |                      ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 6 / 6
• Subtask 2: 41 / 41
• Subtask 3: 0 / 53