結果

問題 No.5020 Averaging
ユーザー square1001
提出日時 2024-02-25 17:33:31
言語 C++17(gcc12)
(gcc 12.3.0 + boost 1.87.0)
結果
AC  
実行時間 812 ms / 1,000 ms
コード長 2,713 bytes
コンパイル時間 2,562 ms
コンパイル使用メモリ 219,288 KB
実行使用メモリ 458,904 KB
スコア 86,102,336
最終ジャッジ日時 2024-02-25 17:34:22
合計ジャッジ時間 41,500 ms
ジャッジサーバーID
（参考情報） 		judge13 / judge12
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ファイルパターン 結果
other AC * 50
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ソースコード

diff #
プレゼンテーションモードにする

#include <bits/stdc++.h>
using namespace std;
class state {
public:
    double x, y; uint64_t bit; int pre;
    state() : x(0.0), y(0.0), bit(0), pre(-1) {}
    state(double x_, double y_, uint64_t bit_, int pre_) : x(x_), y(y_), bit(bit_), pre(pre_) {}
    double score() const {
        return max(abs(x), abs(y));
    }
    bool operator<(const state& s) const {
        return score() < s.score();
    }
};
int main() {
    // step #1. input
    int N;
    cin >> N;
    vector<double> A(N), B(N);
    for (int i = 0; i < N; i++) {
        cin >> A[i] >> B[i];
        A[i] -= 5.0e+17;
        B[i] -= 5.0e+17;
    }
    
    // step #2. beam search
    const int BEAMWIDTH = 16000;
    vector<vector<state> > beam(N);
    for (int i = 1; i < N; i++) {
        uint64_t bit = ((1ULL << N) - 1) ^ (1ULL << i);
        beam[0].push_back(state(A[i] * 0.5, B[i] * 0.5, bit, -1));
    }
    sort(beam[0].begin(), beam[0].end());
    if (int(beam[0].size()) > BEAMWIDTH) {
        beam[0].resize(BEAMWIDTH);
    }
    for (int level = 1; level <= N - 1; level++) {
        double mul = pow(0.5, min(level + 1, N - 1));
        for (int i = 0; i < int(beam[level - 1].size()); i++) {
            state s = beam[level - 1][i];
            uint64_t b = s.bit;
            while (b != 0) {
                int pos = __builtin_ctzll(b);
                b ^= 1ULL << pos;
                double x = s.x + A[pos] * mul;
                double y = s.y + B[pos] * mul;
                uint64_t bit = s.bit ^ (1ULL << pos);
                beam[level].push_back(state(x, y, bit, i));
            }
        }
        if (int(beam[level].size()) > BEAMWIDTH) {
            nth_element(beam[level].begin(), beam[level].begin() + BEAMWIDTH, beam[level].end());
            beam[level].resize(BEAMWIDTH);
        }
        cerr << "level = " << level << ": size = " << beam[level].size() << ", score = " << (*min_element(beam[level].begin(), beam[level].end
            ())).score() << ", back = " << beam[level].back().score() << endl;
    }
    
    // step #3. construct depth
    vector<int> depth(N, -1);
    int idx = min_element(beam[N - 1].begin(), beam[N - 1].end()) - beam[N - 1].begin();
    uint64_t prebit = beam[N - 1][idx].bit;
    for (int i = N - 1; i >= 0; i--) {
        uint64_t nxtbit = (i != 0 ? beam[i - 1][beam[i][idx].pre].bit : (1ULL << N) - 1);
        uint64_t bitdiff = prebit ^ nxtbit;
        depth[__builtin_ctzll(bitdiff)] = min(i + 1, N - 1);
        prebit = nxtbit;
        if (i != 0) {
            idx = beam[i][idx].pre;
        }
    }
    
    // step #4. construct answer
    vector<array<int, 2> > answer;
    vector<int> curdepth = depth;
    while (curdepth[0] != 0) {
        int p1 = max_element(curdepth.begin(), curdepth.end()) - curdepth.begin();
        int p2 = max_element(curdepth.begin() + p1 + 1, curdepth.end()) - curdepth.begin();
        answer.push_back({p1, p2});
        curdepth[p1] -= 1;
        curdepth[p2] = -1;
    }
    
    // step #5. output
    cout << answer.size() << endl;
    for (array<int, 2> v : answer) {
        cout << v[0] + 1 << ' ' << v[1] + 1 << endl;
    }
    
    return 0;
}
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