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Shiroha白羽的博客

Golang 踩坑 —— interface 为参数的时候传 nil 指针 Codeforces Round 925 (Div. 3) Codeforces Round 924 (Div. 2) Codeforces Round 923 (Div. 3) Codeforces Round 922 (Div. 2) Codeforces Round 921 (Div. 2) Educational Codeforces Round 161 (Rated for Div. 2) Codeforces Round 920 (Div. 3) Codeforces Round 919 (Div. 2) Hello 2024 Good Bye 2023 Codeforces Round 918 (Div. 4) 个人备份的常用 macOS 清理命令 Codeforces Round 917 (Div. 2) Pinely Round 3 (Div. 1 + Div. 2) Educational Codeforces Round 160 (Rated for Div. 2) Codeforces Round 915 (Div. 2) Codeforces Round 914 (Div. 2) Codeforces Round 913 (Div. 3) Educational Codeforces Round 159 (Rated for Div. 2) Codeforces Round 912 (Div. 2) Codeforces Round 911 (Div. 2) CodeTON Round 7 (Div. 1 + Div. 2, Rated, Prizes!) Educational Codeforces Round 158 (Rated for Div. 2) Codeforces Round 910 (Div. 2) Codeforces Round 909 (Div. 3) Codeforces Round 908 (Div. 2) Educational Codeforces Round 157 (Rated for Div. 2) C++自定义的字面量 Codeforces Round 907 (Div. 2)
Strassen算法代码
Shiroha · 2021-10-13 · via Shiroha白羽的博客
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/**
* Created by Mauve on 3/29/2020.
* Copyright © 2020 Mauve, All Rights Reserved
*/

#include <bits/stdc++.h>

using namespace std;

/**
* 矩阵相乘
* 最终结果耗时结果保存至
* https://www.desmos.com/calculator/gl4tm5i1zu
*/

struct mat {
unsigned row, col;

mat(unsigned r, unsigned c) : row(r), col(c) {}

virtual int &pos_ref(unsigned i, unsigned j) = 0;

virtual int pos(unsigned i, unsigned j) const = 0;
};

struct base_mat;
struct sub_mat;

stack<sub_mat *> sub_data;

struct base_mat : mat {
int *data;

base_mat(unsigned r, unsigned c) : mat(r, c), data(new int[row * col]) {}

~base_mat() {
delete[] data;
}

inline int &pos_ref(unsigned i, unsigned j) override {
return *(data + i * col + j);
}

inline int pos(unsigned i, unsigned j) const override {
return *(data + i * col + j);
}
};

unsigned min_mul;

struct sub_mat : mat {
mat *a, *b;
bool is_add;
unsigned offset_ai, offset_aj, offset_bi, offset_bj;

explicit sub_mat(mat *data) : mat(data->row, data->col), a(data), b(nullptr),
is_add(false), offset_ai(0), offset_aj(0),
offset_bi(0), offset_bj(0) { sub_data.push(this); }

sub_mat(mat *data, bool of_i, bool of_j) : mat(data->row >> 1u, data->col >> 1u), a(data), b(nullptr),
is_add(false), offset_ai(of_i ? data->row >> 1u : 0),
offset_aj(of_j ? data->col >> 1u : 0),
offset_bi(0), offset_bj(0) { sub_data.push(this); }

inline int &pos_ref(unsigned i, unsigned j) override {
assert(b == nullptr);
return a->pos_ref(i + offset_ai, j + offset_aj);
}

inline int pos(unsigned i, unsigned j) const override {
if (b == nullptr)
return a->pos(i + offset_ai, j + offset_aj);
return a->pos(i + offset_ai, j + offset_aj) + (is_add ? 1 : -1) * b->pos(i + offset_bi, j + offset_bj);
}

inline sub_mat *operator+(sub_mat &other) {
auto res = new sub_mat(this);
res->b = &other;
res->is_add = true;
return res;
}

inline sub_mat *operator-(sub_mat &other) {
auto res = new sub_mat(this);
res->b = &other;
res->is_add = false;
return res;
}

mat *operator*(sub_mat &other) {
assert(col == other.row);
auto res = new base_mat(row, other.col);
if (col & 1u || row & 1u || other.col & 1u || col <= min_mul || row <= min_mul || other.col <= min_mul) {
memset(res->data, 0, sizeof(int) * res->row * res->col);
for (int k = 0; k < col; k++)
for (int i = 0; i < row; ++i)
for (int j = 0; j < other.col; ++j)
res->pos_ref(i, j) += pos(i, k) * other.pos(k, j);
} else {
size_t sub_data_size = sub_data.size();
#define a(i, j) (*new sub_mat(this, i == 2 , j == 2))
#define b(i, j) (*new sub_mat(&other, i == 2 , j == 2))
auto m1 = *(a(1, 1) + a(2, 2)) * *(b(1, 1) + b (2, 2));
auto m2 = *(a(2, 1) + a(2, 2)) * b(1, 1);
auto m3 = a(1, 1) * *(b(1, 2) - b(2, 2));
auto m4 = a(2, 2) * *(b(2, 1) - b(1, 1));
auto m5 = *(a(1, 1) + a(1, 2)) * b(2, 2);
auto m6 = *(a(2, 1) - a(1, 1)) * *(b(1, 1) + b(1, 2));
auto m7 = *(a(1, 2) - a(2, 2)) * *(b(2, 1) + b(2, 2));
#undef a
#undef b
unsigned half_row = row >> 1u, half_col = col >> 1u;
#define m(t) (m##t->pos(i, j))
// C11
for (unsigned i = 0; i < half_row; ++i)
for (unsigned j = 0; j < half_col; ++j)
res->pos_ref(i, j) = m(1) + m(4) - m(5) + m(7);
// C12
for (unsigned i = 0; i < half_row; ++i)
for (unsigned j = 0; j < half_col; ++j)
res->pos_ref(i, j + half_col) = m(3) + m(5);
// C21
for (unsigned i = 0; i < half_row; ++i)
for (unsigned j = 0; j < half_col; ++j)
res->pos_ref(i + half_row, j) = m(2) + m(4);
// C22
for (unsigned i = 0; i < half_row; ++i)
for (unsigned j = 0; j < half_col; ++j)
res->pos_ref(i + half_row, j + half_col) = m(1) - m(2) + m(3) + m(6);
#undef m
delete dynamic_cast<base_mat *>(m1);
delete dynamic_cast<base_mat *>(m2);
delete dynamic_cast<base_mat *>(m3);
delete dynamic_cast<base_mat *>(m4);
delete dynamic_cast<base_mat *>(m5);
delete dynamic_cast<base_mat *>(m6);
delete dynamic_cast<base_mat *>(m7);
while (sub_data.size() > sub_data_size) {
delete sub_data.top();
sub_data.pop();
}
}
return res;
}
};

unsigned N = 2;

void solve() {
cerr << "N = " << N << endl;
base_mat a(N, N), b(N, N);
for (int i = 0; i < N; ++i)
for (int j = 0; j < N; ++j)
cin >> a.pos_ref(i, j);
for (int i = 0; i < N; ++i)
for (int j = 0; j < N; ++j)
cin >> b.pos_ref(i, j);

for (int t = 1; t < min(10u, N); t += 3) {
auto x = new sub_mat(&a), y = new sub_mat(&b);
min_mul = t;

auto time_1 = clock();
auto z = *x * *y;
auto time_2 = clock();

cerr << "t = " << t << " time: " << double(time_2 - time_1) / CLOCKS_PER_SEC << endl;
delete dynamic_cast<base_mat *>(z);
while (!sub_data.empty()) {
delete sub_data.top();
sub_data.pop();
}
}

auto x = new sub_mat(&a), y = new sub_mat(&b);
min_mul = 10000;

auto time_1 = clock();
auto z = *x * *y;
auto time_2 = clock();

cerr << "tradition: " << double(time_2 - time_1) / CLOCKS_PER_SEC << endl;
delete dynamic_cast<base_mat *>(z);
while (!sub_data.empty()) {
delete sub_data.top();
sub_data.pop();
}
N *= 2;
if (N >= 1000) exit(0);
}

signed main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
#ifdef ACM_LOCAL
freopen("in.txt", "r", stdin);
freopen("out.txt", "w", stdout);
long long test_index_for_debug = 1;
char acm_local_for_debug;
while (cin >> acm_local_for_debug && acm_local_for_debug != '~') {
cin.putback(acm_local_for_debug);
if (test_index_for_debug > 20) {
throw runtime_error("Check the stdin!!!");
}
auto start_clock_for_debug = clock();
solve();
auto end_clock_for_debug = clock();
cout << "Test " << test_index_for_debug << " successful" << endl;
cerr << "Test " << test_index_for_debug++ << " Run Time: "
<< double(end_clock_for_debug - start_clock_for_debug) / CLOCKS_PER_SEC << "s" << endl;
cout << "--------------------------------------------------" << endl;
}
#else
solve();
#endif
return 0;
}