Submission #978162

#	Time	Username	Problem	Language	Result	Execution time	Memory
978162		LOLOLO	Traffic (IOI10_traffic)	C++17	0 / 100	2 ms	14680 KiB

traffic

#include <bits/stdc++.h>
#define ll long long
using namespace std;

#define           f     first
#define           s     second
#define           pb    push_back
#define           ep    emplace
#define           eb    emplace_back
#define           lb    lower_bound
#define           ub    upper_bound
#define       all(x)    x.begin(), x.end()
#define      rall(x)    x.rbegin(), x.rend()
#define   uniquev(v)    sort(all(v)), (v).resize(unique(all(v)) - (v).begin())
#define     mem(f,x)    memset(f , x , sizeof(f))
#define        sz(x)    (int)(x).size()
#define  __lcm(a, b)    (1ll * ((a) / __gcd((a), (b))) * (b))
#define          mxx    *max_element
#define          mnn    *min_element
#define    cntbit(x)    __builtin_popcountll(x)
#define       len(x)    (int)(x.length())

const int N = 3e5 + 10;
vector <int> ed[N];
ll f[N], a[N], sz[N];

void dfs(int u, int v) {
    for (auto x : ed[u]) {
        if (x == v)
            continue;
            
        sz[u]++;
        dfs(x, u);
        f[u] = max(f[u], f[x] + a[x]);
    }
}

//before -> u is v's parent
void reroot(int u, int v) {
    f[v] = max(f[v], f[u] + a[u]);
}

ll ans = 1e18, id = 0;
void dfs2(int u, int v) {
    if (ans > f[u]) {
        ans = f[u];
        id = u;
    }

    sort(all(ed[u]), [&] (int x, int y) {return f[x] + a[x] > f[y] + a[y];});
    for (int i = 0; i < sz(ed[u]); i++) {
        int x = ed[u][i];
        if (x == v)
            continue;

        ll p1 = f[u], p2 = f[x];
        if (sz[u] == 1) {
            f[u] = 0;
        } else {
            if (i == 0) {
                f[u] = f[ed[u][1]] + a[ed[u][1]];
            } else {
                f[u] = f[ed[u][0]] + a[ed[u][0]];
            }
        }

        reroot(u, x);
        dfs2(x, u);
        f[u] = p1, f[x] = p2;
    }
}

int LocateCentre(int n, int P[], int S[], int D[]) {
    ans = 1e18;
    for (int i = 0; i < n - 1; i++) {
        ed[S[i]].pb(D[i]);
        ed[D[i]].pb(S[i]);
    }

    for (int i = 1; i <= n; i++)
        a[i] = P[i - 1];

    dfs(1, 1);
    dfs2(1, 1);
    return id;
}

• Subtask 1: 0 / 25
• Subtask 2: 0 / 25
• Subtask 3: 0 / 25
• Subtask 4: 0 / 25