Test/Aizu Online Judge/ALDS1/ALDS1_11_D.test.cpp

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• Last update: 2023-12-31 11:07:57+09:00
• Problem: https://onlinejudge.u-aizu.ac.jp/courses/lesson/1/ALDS1/5/ALDS1_11_D

Depends on

• Union Find (Graph/dsu.hpp)

Code

#define PROBLEM "https://onlinejudge.u-aizu.ac.jp/courses/lesson/1/ALDS1/5/ALDS1_11_D"

#include <bits/stdc++.h>

#include "Graph/dsu.hpp"

using namespace std;

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n, m, q, u, v;
    cin >> n >> m;
    dsu uf(n);
    while(m--){
        cin >> u >> v;
        uf.merge(u, v);
    }
    cin >> q;
    while(q--){
        cin >> u >> v;
        cout << (uf.same(u, v) ? "yes" : "no") << '\n';
    }
}

#line 1 "Test/Aizu Online Judge/ALDS1/ALDS1_11_D.test.cpp"
#define PROBLEM "https://onlinejudge.u-aizu.ac.jp/courses/lesson/1/ALDS1/5/ALDS1_11_D"

#include <bits/stdc++.h>

#line 1 "Graph/dsu.hpp"
struct dsu {
    public:
    dsu() : _n(0) {}
    dsu(int n) : _n(n), num_component(n), parent_or_size(n, -1) {}

    int merge(int a, int b) {
        assert(0 <= a && a < _n);
        assert(0 <= b && b < _n);
        int x = leader(a), y = leader(b);
        if (x == y) return x;
        if (-parent_or_size[x] < -parent_or_size[y]) std::swap(x, y);
        parent_or_size[x] += parent_or_size[y];
        parent_or_size[y] = x;
        num_component--;
        return x;
    }

    bool same(int a, int b) {
        assert(0 <= a && a < _n);
        assert(0 <= b && b < _n);
        return leader(a) == leader(b);
    }

    int leader(int a) {
        assert(0 <= a && a < _n);
        if (parent_or_size[a] < 0) return a;
        return parent_or_size[a] = leader(parent_or_size[a]);
    }

    int size() { 
        return num_component;
    }

    int size(int a) {
        assert(0 <= a && a < _n);
        return -parent_or_size[leader(a)];
    }

    std::vector<std::vector<int>> groups() {
        std::vector<int> leader_buf(_n), group_size(_n);
        for (int i = 0; i < _n; i++) {
            leader_buf[i] = leader(i);
            group_size[leader_buf[i]]++;
        }
        std::vector<std::vector<int>> result(_n);
        for (int i = 0; i < _n; i++) {
            result[i].reserve(group_size[i]);
        }
        for (int i = 0; i < _n; i++) {
            result[leader_buf[i]].push_back(i);
        }
        result.erase(
            std::remove_if(result.begin(), result.end(),
                           [&](const std::vector<int>& v) { return v.empty(); }),
            result.end());
        return result;
    }

    private:
    int _n, num_component;
    // root node: -1 * component size
    // otherwise: parent
    std::vector<int> parent_or_size;
};
#line 5 "Test/Aizu Online Judge/ALDS1/ALDS1_11_D.test.cpp"
using namespace std;

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n, m, q, u, v;
    cin >> n >> m;
    dsu uf(n);
    while(m--){
        cin >> u >> v;
        uf.merge(u, v);
    }
    cin >> q;
    while(q--){
        cin >> u >> v;
        cout << (uf.same(u, v) ? "yes" : "no") << '\n';
    }
}

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