Submission #1259235

#	Time	Username	Problem	Language	Result	Execution time	Memory
1259235		son2008	Election Campaign (JOI15_election_campaign)	C++20	100 / 100	117 ms	35144 KiB

election_campaign

#include <bits/stdc++.h>
using namespace std;
#define ii pair<int, int>
#define fi first
#define se second
// #define int long long
#define ll long long
#define ld double
#define mp make_pair
#define lg2 30
#define iii pair<int, ii>
#define iiii pair<ii, ii>
#define base 29
#define eps 1e-8
#define MASK(i) (1LL << (i))
#define BIT(S, i) (((S) >> (i)) & 1)
int dx[] = {0LL, 0LL, 1, -1, 1, 1, -1, -1};
int dy[] = {1, -1, 0LL, 0LL, 1, -1, 1, -1};
const int maxn = 1e5 + 5;
const int mod = 1e9 + 7;
int n, m, x[maxn], y[maxn], a[maxn], b[maxn], c[maxn], h[maxn], tin[maxn], tout[maxn], timer, P[maxn][lg2 + 1], dp[maxn], dp2[maxn];
vector<int> g[maxn], pos[maxn];
void dfs(int u, int cha)
{
    tin[u] = ++timer;
    for (int v : g[u])
    {
        if (v == cha)
            continue;
        P[v][0] = u;
        h[v] = h[u] + 1;
        dfs(v, u);
    }
    tout[u] = timer;
}
void build_lca()
{
    for (int j = 1; j <= lg2; j++)
    {
        for (int i = 1; i <= n; i++)
            P[i][j] = P[P[i][j - 1]][j - 1];
    }
}
int lca(int u, int v)
{
    if (h[u] < h[v])
        swap(u, v);
    for (int i = lg2; i >= 0; i--)
    {
        if (h[u] - h[v] >= (1 << i))
            u = P[u][i];
    }
    if (u == v)
    {
        return u;
    }
    for (int i = lg2; i >= 0; i--)
    {
        if (P[u][i] != P[v][i])
        {
            u = P[u][i];
            v = P[v][i];
        }
    }
    return P[u][0];
}
struct FEN
{
    int n;
    vector<int> bit;
    FEN() {};
    FEN(int _n) : bit(n + 1, 0), n(_n + 1) {
                  };
    int get(int r)
    {
        int ret = 0;
        for (; r >= 0; r = (r & (r + 1)) - 1)
            ret += bit[r];
        return ret;
    }

    int get(int l, int r)
    {
        return get(r) - get(l - 1);
    }

    void update(int idx, int delta)
    {
        for (; idx < n; idx = idx | (idx + 1))
            bit[idx] += delta;
    }
    void updateRange(int l, int r, int val)
    {
        update(l, val);
        update(r + 1, -val);
    }
} bit;
void DFS(int u, int cha)
{
    for (int v : g[u])
    {
        if (v == cha)
            continue;
        DFS(v, u);
        dp2[u] += dp[v];
    }
    dp[u] = dp2[u];
    bit.updateRange(tin[u], tout[u], dp2[u]);
    for (int i : pos[u])
    {
        dp[u] = max(dp[u], bit.get(tin[a[i]]) + bit.get(tin[b[i]]) - 2 * bit.get(tin[P[u][0]]) - dp2[u] + c[i]);
        if (u == 5)
        {
      //      cout << ":" << a[i] << " " << b[i] << " " << bit.get(tin[a[i]]) + bit.get(tin[b[i]]) - 2 * bit.get(tin[P[u][0]]) - dp2[tin[u]] + c[i] << '\n';
        }
    }
  //  cout << u << " " << dp[u] << " " << dp2[u] << '\n';
    bit.updateRange(tin[u], tout[u], -dp[u]);
}
signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
#define task "task"
    if (fopen(task ".inp", "r"))
    {
        freopen(task ".inp", "r", stdin);
        freopen(task ".out", "w", stdout);
    }
    cin >> n;
    for (int i = 1; i < n; i++)
    {
        cin >> x[i] >> y[i];
        g[x[i]].push_back(y[i]);
        g[y[i]].push_back(x[i]);
    }
    dfs(1, -1);
    build_lca();
    cin >> m;
    for (int i = 1; i <= m; i++)
    {
        cin >> a[i] >> b[i] >> c[i];
        pos[lca(a[i], b[i])].push_back(i);
    }
    bit = FEN(n);
    DFS(1, -1);
    cout << dp[1];
    cerr << endl
         << "TIME : " << clock() * 0.001 << "s" << endl;
}

Compilation message (stderr)

election_campaign.cpp: In function 'int main()':
election_campaign.cpp:128:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  128 |         freopen(task ".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
election_campaign.cpp:129:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  129 |         freopen(task ".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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