add chokudai search

Author: tsutaj

docs/marathon/chokudai_search.md

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+- `add_next_states` で状態遷移を定義する
+    - 状態およびそのターン数が与えられるので、次の状態およびそのターン数を決定し、 `register_state` を使って状態を登録
+- メモリ制約に引っかからないように、各ターンで持つ状態数に上限を設けることが可能
+    - `set_max_num_states` で設定する
+    - Interval Heap を使って、あふれた状態を消している
+
+AHC032 で利用実績あり。  
+[https://atcoder.jp/contests/ahc032/submissions/61302590](https://atcoder.jp/contests/ahc032/submissions/61302590)

marathon/chokudai_search.cpp

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+/**
+ * @brief chokudai サーチ
+ * @docs docs/marathon/chokudai_search.md
+ */
+
+#include "interval_heap.cpp"
+
+template <class State, class Timer>
+class ChokudaiSearch {
+   public:
+    ChokudaiSearch() : num_iter_(-1) {}
+    void init(int max_turns, double search_time, int time_check_iter) {
+        states_.resize(max_turns + 1);
+        search_time_ = search_time;
+        num_iter_ = 0;
+        time_check_iter_ = time_check_iter;
+        max_num_states_.resize(max_turns, 1 << 30);
+    }
+    void set_max_num_states(int max_num_state) {
+        fill(max_num_states_.begin(), max_num_states_.end(), max_num_state);
+    }
+    void set_max_num_states(const vector<int> &max_num_states) {
+        assert(max_num_states.size() == max_num_states_.size());
+        max_num_states_ = max_num_states;
+    }
+    void register_state(int turns, const State &state) {
+        states_[turns].emplace(state);
+        while(states_[turns].size() > max_num_states_[turns]) {
+            states_[turns].pop_max();
+        }
+    }
+    void search(Timer &timer, const auto &add_next_states) {
+        assert(num_iter_ >= 0);
+        const double start_time = timer.getTime();
+        for(num_iter_ = 0;; num_iter_++) {
+            for(int turns = 0; turns + 1 < (int)states_.size(); turns++) {
+                if(timer.getTime() - start_time > search_time_) {
+                    goto TIME_OVER;
+                }
+                if(states_[turns].size() == 0) continue;
+                State state = states_[turns].top_min();
+                states_[turns].pop_min();
+                add_next_states(turns, state);
+            }
+        }
+    TIME_OVER:;
+        fprintf(stderr, "chokudai search: num_iter = %d\n", num_iter_);
+    }
+    const State &get_best_state() const { return states_.back().top_min(); }
+
+   private:
+    double search_time_;
+    int num_iter_;
+    int time_check_iter_;
+    vector<IntervalHeap<State>> states_;
+    vector<int> max_num_states_;
+};