Submission #965000

#	Time	Username	Problem	Language	Result	Execution time	Memory
965000		Pannda	Swapping Cities (APIO20_swap)	C++17	37 / 100	2033 ms	11340 KiB

swap

#include "swap.h"

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

int n, m;
vector<array<int, 3>> edges;
struct DSU {
    vector<int> f;
    vector<int> siz;
    vector<int> deg;
    vector<bool> ok;

    DSU(int n) : f(n), siz(n, 1), deg(n, 0), ok(n, false) { iota(f.begin(), f.end(), 0); }

    int leader(int u) {
        while (u != f[u]) u = f[u] = f[f[u]];
        return u;
    }

    bool unionize(int u0, int v0) {
        int u = leader(u0);
        int v = leader(v0);
        if (u == v) {
            ok[u] = true;
            return false;
        }
        if (siz[u] > siz[v]) swap(u, v);
        siz[v] += siz[u];
        if (++deg[u0] >= 3 || ++deg[v0] >= 3) ok[v] = true;
        ok[v] = ok[v] | ok[u];
        f[u] = v;
        return true;
    }

    bool same(int u, int v) {
        return leader(u) == leader(v);
    }

    bool isOk(int u) {
        return ok[leader(u)];
    }
};

void init(int N, int M, vector<int> U, vector<int> V, vector<int> W) {
    n = N;
    m = M;
    edges.resize(m);
    for (int i = 0; i < m; i++) {
        edges[i] = {U[i], V[i], W[i]};
    }
    sort(edges.begin(), edges.end(), [&](array<int, 3> e0, array<int, 3> e1) { return e0[2] < e1[2]; });
}

int getMinimumFuelCapacity(int X, int Y) {
    DSU dsu(n);
    for (auto [u, v, w] : edges) {
        dsu.unionize(u, v);
        if (dsu.same(X, Y) && dsu.isOk(X)) return w;
    }
    return -1;
}

• Subtask 1: 0 / 6
• Subtask 2: 0 / 7
• Subtask 3: 17 / 17
• Subtask 4: 20 / 20
• Subtask 5: 0 / 23
• Subtask 6: 0 / 27