Submission #1123076

#	Time	Username	Problem	Language	Result	Execution time	Memory
1123076		Yang8on	Election Campaign (JOI15_election_campaign)	C++20	100 / 100	142 ms	30636 KiB

election_campaign

#include <bits/stdc++.h>
#define Y8o "election_campaign"
#define maxn (int) 1e5 + 5
#define ll long long
#define pii pair<ll, ll>
#define gb(i, j) ((i >> j) & 1)
#define all(x) x.begin(), x.end()
#define _left id * 2, l, mid
#define _right id * 2 + 1, mid + 1, r
#define fi(i, a, b) for(int i = a; i <= b; i ++)
#define fid(i, a, b) for(int i = a; i >= b; i --)

//#define f first
//#define s second

using namespace std;

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll GetRandom(ll l, ll r) {
    return uniform_int_distribution<ll> (l, r) (rng);
}
void iof() {
    ios_base::sync_with_stdio(0);
    cin.tie(NULL), cout.tie(NULL);
    if(fopen(Y8o".inp", "r"))
    {
        freopen(Y8o".inp", "r", stdin);
//        freopen(Y8o".out", "w", stdout);
    }
}
void ctime() {
    cerr << "\n" << "\nTime elapsed: " << 1000 * clock() / CLOCKS_PER_SEC << "ms\n";
}


int n, Q;
vector<int> o[maxn];
int h[maxn], cha[maxn][17];
int in[maxn], out[maxn], cnt;
struct dl { int u, v, w; }; vector<dl> qr[maxn];
ll dp[maxn][2];

void pre_dfs(int u = 1, int p = 0) {
    in[u] = ++cnt;
    for(int v : o[u]) if(v != p) {
        h[v] = h[u] + 1, cha[v][0] = u;
        fi(i, 1, 16) cha[v][i] = cha[ cha[v][i - 1] ][i - 1];
        pre_dfs(v, u);
    }
    out[u] = cnt;
}

int lca(int u, int v) {
    if(h[u] < h[v]) swap(u, v);
    int kc = h[u] - h[v];
    fid(i, 16, 0) if(gb(kc, i)) u = cha[u][i];
    fid(i, 16, 0) if(cha[u][i] != cha[v][i]) u = cha[u][i], v = cha[v][i];
    return u == v ? u : cha[u][0];
}

struct BIT {

    ll bit[maxn];

    void update(int l, int r, ll w) {
        r ++;
        for(; l < maxn; l += (l & -l)) bit[l] += w;
        for(; r < maxn; r += (r & -r)) bit[r] -= w;
    }
    ll get(int x, ll sum = 0) {
        while(x > 0) sum += bit[x], x -= (x & -x);
        return sum;
    }

} Bit[2];

void dfs(int u = 1, int p = 0) {
    for(int v : o[u]) if(v != p) {
        dfs(v, u);
        dp[u][0] += max(dp[v][0], dp[v][1]);
    }
    Bit[0].update(in[u], out[u], dp[u][0]);

    for(dl x : qr[u]) {
        int u1 = x.u, v1 = x.v, w = x.w;
        if(h[u1] > h[v1]) swap(u1, v1);

        ll val1 = Bit[0].get(in[u1]) - Bit[1].get(in[u1]), val2 = Bit[0].get(in[v1]) - Bit[1].get(in[v1]);
        if(u1 == u) {
            dp[u][1] = max(dp[u][1], val2 + w);
        }
        else {
            dp[u][1] = max(dp[u][1], val1 + val2 + w - dp[u][0]);
        }
    }
    Bit[1].update(in[u], out[u], max(dp[u][0], dp[u][1]));
}

void solve() {
    cin >> n ;
    fi(i, 1, n - 1) {
        int u, v; cin >> u >> v;
        o[u].push_back(v), o[v].push_back(u);
    }

    pre_dfs();

    cin >> Q;
    fi(i, 1, Q) {
        int u, v, w; cin >> u >> v >> w;
        int p = lca(u, v);
        qr[p].push_back({ u, v, w });
    }

    dfs();
//    fi(i, 1, n) cout << i << ' ' << dp[i][0] << ' ' << dp[i][1] << '\n';

    cout << max(dp[1][0], dp[1][1]);
}


int main() {
    iof();

    int nTest = 1;
//    cin >> nTest;

    while(nTest --) {
        solve();
    }

    ctime();
    return 0;
}

Compilation message (stderr)

election_campaign.cpp: In function 'void iof()':
election_campaign.cpp:27:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |         freopen(Y8o".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 5 / 5
• Subtask 3: 5 / 5
• Subtask 4: 30 / 30
• Subtask 5: 10 / 10
• Subtask 6: 40 / 40