結果

問題 No.1301 Strange Graph Shortest Path
ユーザー pockynypockyny
提出日時 2020-11-27 21:37:07
言語 C++17
(gcc 13.2.0 + boost 1.83.0)
結果
AC  
実行時間 293 ms / 3,000 ms
コード長 5,583 bytes
コンパイル時間 1,182 ms
コンパイル使用メモリ 100,504 KB
実行使用メモリ 36,420 KB
最終ジャッジ日時 2023-10-10 21:39:18
合計ジャッジ時間 10,759 ms
ジャッジサーバーID
（参考情報） 		judge15 / judge12
このコードへのチャレンジ
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テストケース

テストケース表示
入力 結果 実行時間
実行使用メモリ
testcase_00 AC 1 ms
4,352 KB
testcase_01 AC 1 ms
4,352 KB
testcase_02 AC 231 ms
35,948 KB
testcase_03 AC 196 ms
32,376 KB
testcase_04 AC 271 ms
34,688 KB
testcase_05 AC 212 ms
35,556 KB
testcase_06 AC 248 ms
32,252 KB
testcase_07 AC 236 ms
33,972 KB
testcase_08 AC 203 ms
32,640 KB
testcase_09 AC 212 ms
31,000 KB
testcase_10 AC 201 ms
33,060 KB
testcase_11 AC 246 ms
33,296 KB
testcase_12 AC 241 ms
33,296 KB
testcase_13 AC 223 ms
35,700 KB
testcase_14 AC 241 ms
30,820 KB
testcase_15 AC 215 ms
31,744 KB
testcase_16 AC 267 ms
34,576 KB
testcase_17 AC 253 ms
36,420 KB
testcase_18 AC 229 ms
32,780 KB
testcase_19 AC 225 ms
32,328 KB
testcase_20 AC 250 ms
31,160 KB
testcase_21 AC 246 ms
34,816 KB
testcase_22 AC 262 ms
32,240 KB
testcase_23 AC 227 ms
35,680 KB
testcase_24 AC 264 ms
32,016 KB
testcase_25 AC 260 ms
35,144 KB
testcase_26 AC 235 ms
33,424 KB
testcase_27 AC 231 ms
33,576 KB
testcase_28 AC 209 ms
35,004 KB
testcase_29 AC 293 ms
33,864 KB
testcase_30 AC 236 ms
34,312 KB
testcase_31 AC 251 ms
34,384 KB
testcase_32 AC 1 ms
4,348 KB
testcase_33 AC 171 ms
29,280 KB
testcase_34 AC 225 ms
36,196 KB
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ソースコード

diff # 

#include <iostream>

#include <algorithm>
#include <cassert>
#include <limits>
#include <queue>
#include <vector>

namespace atcoder {

template <class Cap, class Cost> struct mcf_graph {
  public:
    mcf_graph() {}
    mcf_graph(int n) : _n(n), g(n) {}

    int add_edge(int from, int to, Cap cap, Cost cost) {
        assert(0 <= from && from < _n);
        assert(0 <= to && to < _n);
        int m = int(pos.size());
        pos.push_back({from, int(g[from].size())});
        g[from].push_back(_edge{to, int(g[to].size()), cap, cost});
        g[to].push_back(_edge{from, int(g[from].size()) - 1, 0, -cost});
        return m;
    }

    struct edge {
        int from, to;
        Cap cap, flow;
        Cost cost;
    };

    edge get_edge(int i) {
        int m = int(pos.size());
        assert(0 <= i && i < m);
        auto _e = g[pos[i].first][pos[i].second];
        auto _re = g[_e.to][_e.rev];
        return edge{
            pos[i].first, _e.to, _e.cap + _re.cap, _re.cap, _e.cost,
        };
    }
    std::vector<edge> edges() {
        int m = int(pos.size());
        std::vector<edge> result(m);
        for (int i = 0; i < m; i++) {
            result[i] = get_edge(i);
        }
        return result;
    }

    std::pair<Cap, Cost> flow(int s, int t) {
        return flow(s, t, std::numeric_limits<Cap>::max());
    }
    std::pair<Cap, Cost> flow(int s, int t, Cap flow_limit) {
        return slope(s, t, flow_limit).back();
    }
    std::vector<std::pair<Cap, Cost>> slope(int s, int t) {
        return slope(s, t, std::numeric_limits<Cap>::max());
    }
    std::vector<std::pair<Cap, Cost>> slope(int s, int t, Cap flow_limit) {
        assert(0 <= s && s < _n);
        assert(0 <= t && t < _n);
        assert(s != t);
        // variants (C = maxcost):
        // -(n-1)C <= dual[s] <= dual[i] <= dual[t] = 0
        // reduced cost (= e.cost + dual[e.from] - dual[e.to]) >= 0 for all edge
        std::vector<Cost> dual(_n, 0), dist(_n);
        std::vector<int> pv(_n), pe(_n);
        std::vector<bool> vis(_n);
        auto dual_ref = [&]() {
            std::fill(dist.begin(), dist.end(),
                      std::numeric_limits<Cost>::max());
            std::fill(pv.begin(), pv.end(), -1);
            std::fill(pe.begin(), pe.end(), -1);
            std::fill(vis.begin(), vis.end(), false);
            struct Q {
                Cost key;
                int to;
                bool operator<(Q r) const { return key > r.key; }
            };
            std::priority_queue<Q> que;
            dist[s] = 0;
            que.push(Q{0, s});
            while (!que.empty()) {
                int v = que.top().to;
                que.pop();
                if (vis[v]) continue;
                vis[v] = true;
                if (v == t) break;
                // dist[v] = shortest(s, v) + dual[s] - dual[v]
                // dist[v] >= 0 (all reduced cost are positive)
                // dist[v] <= (n-1)C
                for (int i = 0; i < int(g[v].size()); i++) {
                    auto e = g[v][i];
                    if (vis[e.to] || !e.cap) continue;
                    // |-dual[e.to] + dual[v]| <= (n-1)C
                    // cost <= C - -(n-1)C + 0 = nC
                    Cost cost = e.cost - dual[e.to] + dual[v];
                    if (dist[e.to] - dist[v] > cost) {
                        dist[e.to] = dist[v] + cost;
                        pv[e.to] = v;
                        pe[e.to] = i;
                        que.push(Q{dist[e.to], e.to});
                    }
                }
            }
            if (!vis[t]) {
                return false;
            }

            for (int v = 0; v < _n; v++) {
                if (!vis[v]) continue;
                // dual[v] = dual[v] - dist[t] + dist[v]
                //         = dual[v] - (shortest(s, t) + dual[s] - dual[t]) + (shortest(s, v) + dual[s] - dual[v])
                //         = - shortest(s, t) + dual[t] + shortest(s, v)
                //         = shortest(s, v) - shortest(s, t) >= 0 - (n-1)C
                dual[v] -= dist[t] - dist[v];
            }
            return true;
        };
        Cap flow = 0;
        Cost cost = 0, prev_cost = -1;
        std::vector<std::pair<Cap, Cost>> result;
        result.push_back({flow, cost});
        while (flow < flow_limit) {
            if (!dual_ref()) break;
            Cap c = flow_limit - flow;
            for (int v = t; v != s; v = pv[v]) {
                c = std::min(c, g[pv[v]][pe[v]].cap);
            }
            for (int v = t; v != s; v = pv[v]) {
                auto& e = g[pv[v]][pe[v]];
                e.cap -= c;
                g[v][e.rev].cap += c;
            }
            Cost d = -dual[s];
            flow += c;
            cost += c * d;
            if (prev_cost == d) {
                result.pop_back();
            }
            result.push_back({flow, cost});
            prev_cost = cost;
        }
        return result;
    }

  private:
    int _n;

    struct _edge {
        int to, rev;
        Cap cap;
        Cost cost;
    };

    std::vector<std::pair<int, int>> pos;
    std::vector<std::vector<_edge>> g;
};

}  // namespace atcoder


using namespace std;
using namespace atcoder;
int main(){
    int i,n,m; cin >> n >> m;
    mcf_graph<int,long long> g(n);
    int s = 0,t = n - 1;
    for(i=0;i<m;i++){
        int a,b,c,d; cin >> a >> b >> c >> d;
        a--; b--;
        g.add_edge(a,b,1,c); g.add_edge(a,b,1,d);
        g.add_edge(b,a,1,c); g.add_edge(b,a,1,d);
    }
    cout << g.flow(s,t,2LL).second << endl;
}
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