Submission #972815

#	Time	Username	Problem	Language	Result	Execution time	Memory
972815		DAleksa	Swapping Cities (APIO20_swap)	C++17	0 / 100	10 ms	17836 KiB

swap

#include "swap.h"
#include <bits/stdc++.h>

using namespace std;

int tsz;

struct DSU {
    int n;
    vector<int> parent, sz;
    vector<bool> chain;
    vector<vector<int>> comp;
    vector<int> id;
    DSU(int _n) {
        n = _n;
        parent.resize(n);
        sz.resize(n);
        comp.resize(n);
        chain.resize(n);
        id.resize(n);
        for(int i = 0; i < n; i++) {
            parent[i] = i;
            sz[i] = 1;
            chain[i] = true;
            comp[i].push_back(i);
            id[i] = i;
        }
    }
    int find_parent(int u) {
        if(parent[u] == u) return u;
        return parent[u] = find_parent(parent[u]);
    }
    bool check(int u, int v) {
        u = find_parent(u);
        v = find_parent(v);
        return u == v;
    }
    void join(int u, int v) {
        u = find_parent(u);
        v = find_parent(v);
        if(sz[u] > sz[v]) swap(u, v);
        for(int i : comp[u]) comp[v].push_back(i);
        comp[u].clear();
        parent[u] = v;
        id[v] = tsz;
    }
    void update_chain_state(int u) {
        u = find_parent(u);
        chain[u] = false;
    }
    int get_size(int u) {
        u = find_parent(u);
        return sz[u];
    }
};

const int N = 1e5 + 10, LOG = 17;
bool leaf[N];
DSU dsu(N);
int order[N];
vector<int> g[2 * N];
int up[2 * N][LOG + 1];
int root;
int timer;
int tin[2 * N], tout[2 * N];
int ans[2 * N];

void dfs(int u, int par) {
    tin[u] = ++timer;
    for(int v : g[u]) {
        dfs(v, u);
        up[v][0] = u;
    }
    tout[u] = ++timer;
}

bool is_ancestor(int u, int v) { return tin[u] <= tin[v] && tout[u] >= tout[v]; }
int LCA(int u, int v) {
    if(is_ancestor(u, v)) return u;
    if(is_ancestor(v, u)) return v;
    for(int j = LOG - 1; j >= 0; j--) {
        if(up[u][j] == 0) continue;
        if(is_ancestor(up[u][j], v)) continue;
        u = up[u][j];
    }
    return up[u][0];
}

void init(int n, int m, vector<int> U, vector<int> V, vector<int> W) {
    for(int i = 0; i < N; i++) leaf[i] = true;
    tsz = n;
    for(int i = 0; i < m; i++) order[i] = i;
    sort(order, order + m, [&](int i, int j) { return W[i] < W[j]; });
    for(int i = 0; i < m; i++) {
        int u = U[order[i]], v = V[order[i]];
        if(dsu.check(u, v)) {
            int par = dsu.find_parent(u);
            if(dsu.chain[par]) {
                for(int j : dsu.comp[par]) {
                    g[tsz].push_back(j);
                }
                ans[tsz] = W[order[i]];
                tsz++;
                dsu.update_chain_state(par);
            }
        } else {
            if(!dsu.chain[dsu.find_parent(u)] || !dsu.chain[dsu.find_parent(v)]) {
                if(dsu.chain[dsu.find_parent(u)]) {
                    for(int j : dsu.comp[dsu.find_parent(u)]) g[tsz].push_back(j);
                } else g[tsz].push_back(dsu.id[dsu.find_parent(u)]);
                if(dsu.chain[dsu.find_parent(v)]) {
                    for(int j : dsu.comp[dsu.find_parent(v)]) g[tsz].push_back(j);
                } else g[tsz].push_back(dsu.id[dsu.find_parent(v)]);
                dsu.join(u, v);
                ans[tsz] = W[order[i]];
                tsz++;
            } else {
                if(leaf[u] && leaf[v]) {
                    if(dsu.get_size(u) > 1) leaf[u] = false;
                    if(dsu.get_size(v) > 1) leaf[v] = false;
                    dsu.join(u, v);
                } else {
                    for(int j : dsu.comp[dsu.find_parent(u)]) g[tsz].push_back(j);
                    for(int j : dsu.comp[dsu.find_parent(v)]) g[tsz].push_back(j);
                    dsu.join(u, v);
                    ans[tsz] = W[order[i]];
                    tsz++;
                    dsu.update_chain_state(u);
                }
            }
        }
    }
//    for(int i = 0; i < tsz; i++) {
//        cout << i << ": ";
//        for(int j : g[i]) cout << j << " ";
//        cout << "\n";
//    }
    root = tsz - 1;
    dfs(root, -1);
    for(int j = 1; j < LOG; j++) for(int i = 0; i <= root; i++) up[i][j] = up[up[i][j - 1]][j - 1];
}

int getMinimumFuelCapacity(int X, int Y) {
    return ans[LCA(X, Y)];
}

/*

5 6
0 1 4
0 2 4
1 2 1
1 3 2
1 4 10
2 3 3
3
1 2
2 4
0 1

*/

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