lamda functions

main.cpp

#include <iostream>
#include <functional>
#include <string>
#include <vector>
#include <map>

// 4 24   +2 + остаток от деления x на 5 +1    9 или 18

static int count, branch_count;

std::function<void (int, int, std::string)> calculate = [](int x, int y, std::string path) {
  branch_count++;

  if (x < y) {
    calculate(x + 2, y, path + "+2 ");

    if (x % 5 != 0) {
      calculate(x + (x % 5) + 1, y, path + "+(x%5)+1 ");
    }
  } else if (x == y) {
    count++;

    std::cout << path << "\n";
  }
};

std::function<void (int, int, std::string)> calculate_reverse = [](int x, int y, std::string path) {
  branch_count++;

  if (x < y) {
    calculate_reverse(x, y - 2, path + "-2 ");

    if (y % 5 != 1) {
      std::string t = "";
      for (auto i = (y - 1) % 5; i < y; i += 5) {
        calculate_reverse(x, y - i, path + "-(y%5)" + t + " ");
        t = t + "-5";
      }
    }
  } else if (x == y) {
    count++;

    std::cout << path << "\n";
  }
};

static const int goal1 = 9, goal2 = 18;

std::function<void (int, int, std::string, int)> calculate_with_goals = [](int x, int y, std::string path, bool pass) {
  branch_count++;

  if (x <= goal2 || pass == true) {
    if (x == goal1 || x == goal2) {
      pass = true;
    }

    if (x < y) {
      calculate_with_goals(x + 2, y, path + "+2 ", pass);

      if (x % 5 != 0) {
        calculate_with_goals(x + (x % 5) + 1, y, path + "+(x%5)+1 ", pass);
      }
    } else if (x == y) {
      count++;

      std::cout << path << "\n";
    }
  }
};

static std::map<int, int> map;

std::function<int (int, int, std::string)> calculate_with_research = [](int x, int y, std::string path) {
  branch_count++;
  int this_count = 0;

  auto it = map.find(x);

  if (it != map.end()) {
    count += it->second;
    this_count = it->second;
  } else {
    if (x < y) {
      this_count += calculate_with_research(x + 2, y, path + "+2 ");

      if (x % 5 != 0) {
        this_count += calculate_with_research(x + (x % 5) + 1, y, path + "+(x%5)+1 ");
      }
    } else if (x == y) {
      count++;
      this_count++;
    }
  }

  map.insert(std::pair<int, int>(x, this_count));
  return this_count;
};

int main() {
  int x, y;
  
  std::cin >> x >> y;

  count = 0; branch_count = 0;
  calculate(x, y, "");
  // 41; 267

  std::cout << "Count: " << count << "\n";
  std::cout << "Branch Count: " << branch_count << "\n";
  std::cout << "\n";

  // ------------------------------------------------------------

  count = 0; branch_count = 0;
  calculate_reverse(x, y, "");
  // 33; 429

  std::cout << "Count: " << count << "\n";
  std::cout << "Branch Count: " << branch_count << "\n";
  std::cout << "\n";

  // ------------------------------------------------------------

  count = 0; branch_count = 0;
  calculate_with_goals(x, y, "", false);
  // 29; 191

  std::cout << "Count: " << count << "\n";
  std::cout << "Branch Count: " << branch_count << "\n";
  std::cout << "\n";

  // ------------------------------------------------------------

  count = 0; branch_count = 0;
  calculate_with_research(x, y, "");
  // 41; 34

  std::cout << "Count: " << count << "\n";
  std::cout << "Branch Count: " << branch_count << "\n";
  std::cout << "\n";

  for (auto it = map.begin(); it != map.end(); it++) {
    std::cout << it->first << ": " << it->second << "\n";
  }
}