CompressedSparseRow
(src/graph/compressed_sparse_row.hpp)

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• Last update: 2024-11-09 01:34:39+09:00
• Include: #include "src/graph/compressed_sparse_row.hpp"

CompressedSparseRow

vector<vector<int>> などをアーキテクチャ的に高速化するための構造体です．
基本的には内部的にしか使用しないと思うので，把握する必要はありません．

Depends on

• Graph (src/graph/graph_template.hpp)
• template (src/template/template.hpp)

Required by

• strongly_connected_components (src/graph/strongly_connected_components.hpp)
• TwoSAT (src/math/two_sat.hpp)

Verified with

• verify/aizu_online_judge/grl/strongly_connected_components.test.cpp
• verify/library_checker/graph/strongly_connected_components.test.cpp
• verify/library_checker/other/2_sat.test.cpp

Code

#pragma once
#include "../template/template.hpp"
#include "./graph_template.hpp"
template <typename T>
struct CompressedSparseRow {
    vector<int> start, elist;
    CompressedSparseRow(const Graph<T>& g)
        : start(g.size() + 1), elist(g.edge_size()) {
        const int n = g.size();
        for(int i = 0; i < n; ++i) {
            start[i + 1] = start[i] + g[i].size();
            int counter = start[i];
            for(const Edge<T>& e : g[i]) {
                elist[counter++] = e.to;
            }
        }
    }
};

#line 2 "src/template/template.hpp"
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<long long, long long>;
#define rep(i, a, b) for(long long i = (a); i < (b); ++i)
#define rrep(i, a, b) for(long long i = (a); i >= (b); --i)
constexpr long long inf = 4e18;
struct SetupIO {
    SetupIO() {
        ios::sync_with_stdio(0);
        cin.tie(0);
        cout << fixed << setprecision(30);
    }
} setup_io;
#line 3 "src/graph/graph_template.hpp"
template <typename T>
struct Edge {
    int from, to;
    T cost;
    int idx;
    Edge()
        : from(-1), to(-1), cost(-1), idx(-1) {}
    Edge(const int from, const int to, const T& cost = 1, const int idx = -1)
        : from(from), to(to), cost(cost), idx(idx) {}
    operator int() const {
        return to;
    }
};
template <typename T>
struct Graph {
    Graph(const int N)
        : n(N), es(0), g(N) {}
    int size() const {
        return n;
    }
    int edge_size() const {
        return es;
    }
    void add_edge(const int from, const int to, const T& cost = 1) {
        assert(0 <= from and from < n);
        assert(0 <= to and to < n);
        g[from].emplace_back(from, to, cost, es);
        g[to].emplace_back(to, from, cost, es++);
    }
    void add_directed_edge(const int from, const int to, const T& cost = 1) {
        assert(0 <= from and from < n);
        assert(0 <= to and to < n);
        g[from].emplace_back(from, to, cost, es++);
    }
    inline vector<Edge<T>>& operator[](const int& k) {
        assert(0 <= k and k < n);
        return g[k];
    }
    inline const vector<Edge<T>>& operator[](const int& k) const {
        assert(0 <= k and k < n);
        return g[k];
    }

   private:
    int n, es;
    vector<vector<Edge<T>>> g;
};
template <typename T>
using Edges = vector<Edge<T>>;
#line 4 "src/graph/compressed_sparse_row.hpp"
template <typename T>
struct CompressedSparseRow {
    vector<int> start, elist;
    CompressedSparseRow(const Graph<T>& g)
        : start(g.size() + 1), elist(g.edge_size()) {
        const int n = g.size();
        for(int i = 0; i < n; ++i) {
            start[i + 1] = start[i] + g[i].size();
            int counter = start[i];
            for(const Edge<T>& e : g[i]) {
                elist[counter++] = e.to;
            }
        }
    }
};

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