72 lines
2.0 KiB
C++
72 lines
2.0 KiB
C++
#include <iostream>
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#include <unordered_map>
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class SolutionOFOneTwoStep {
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private:
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static std::unordered_map<size_t, size_t> result_;
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public:
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enum class POLICY {
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RECURSIVE,
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NONRECURSIVE
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};
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private:
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size_t recursive(size_t steps) {
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auto iter = result_.find(steps);
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if (result_.end() != iter) { // found.
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return iter->second;
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} else {
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size_t res = operator()(steps - 1) + operator()(steps - 2);
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result_.insert({steps, res});
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return res;
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}
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}
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size_t nonrecursive(size_t steps) {
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auto iter = result_.find(steps);
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if (result_.end() != iter) { // found.
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return iter->second;
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} else {
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size_t start;
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for (start = steps; start != 2 and result_.end() == result_.find(start); --start) {}
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for (size_t i = start; i != steps; ++i) {
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result_.insert({i + 1, result_[i - 1] + result_[i]});
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}
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return result_[steps];
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}
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}
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public:
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size_t operator()(size_t steps, const POLICY policy = POLICY::RECURSIVE) {
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if (policy == POLICY::RECURSIVE) {
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return recursive(steps);
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} else if (policy == POLICY::NONRECURSIVE) {
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return nonrecursive(steps);
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}
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}
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static void debug() {
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for (auto kv : result_) {
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std::cout << kv.first << ' ' << kv.second << std::endl;
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}
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std::cout << std::endl;
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}
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};
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std::unordered_map<size_t, size_t> SolutionOFOneTwoStep::result_ = {{1, 1}, {2, 2}};
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int main() {
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SolutionOFOneTwoStep::debug();
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std::cout << SolutionOFOneTwoStep()(5, SolutionOFOneTwoStep::POLICY::RECURSIVE) << std::endl;
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SolutionOFOneTwoStep::debug();
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std::cout << SolutionOFOneTwoStep()(10, SolutionOFOneTwoStep::POLICY::NONRECURSIVE) << std::endl;
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SolutionOFOneTwoStep::debug();
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std::cout << SolutionOFOneTwoStep()(20, SolutionOFOneTwoStep::POLICY::RECURSIVE) << std::endl;
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SolutionOFOneTwoStep::debug();
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return 0;
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}
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