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120.cc
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#include <algorithm>
#include <iostream>
#include <sstream>
#include <string>
#include <vector>
#ifdef ONLINE_JUDGE
#define NDEBUG
#endif
#include <assert.h>
const int MAX_NUM_PANCAKES = 30;
const int MAX_DIAMETER = 100;
class PancakeStack {
public:
friend std::istream& operator>>(std::istream& in, PancakeStack& stack);
friend std::ostream& operator<<(std::ostream& out, const PancakeStack& stack);
PancakeStack() {}
PancakeStack(const PancakeStack& other) : pancakes_(other.pancakes_) {}
int num_pancakes() const { return pancakes_.size(); }
int diameter(int i) const {
assert(0 <= i && i < static_cast<int>(pancakes_.size()));
return pancakes_[i];
}
typedef std::vector<int>::const_iterator const_iterator;
const_iterator begin() const { return pancakes_.begin(); }
const_iterator end() const { return pancakes_.end(); }
// Insert the spatula between i-th and (i+1)-th pancake; reverse from
// pancakes 0 to pancake i (both ends are inclusive).
void Flip(int i) {
std::reverse(pancakes_.begin(), pancakes_.begin() + i + 1);
}
void Sort() { std::sort(pancakes_.begin(), pancakes_.end()); }
private:
// Top pancake at index 0, not n.
std::vector<int> pancakes_;
};
class Flips {
public:
explicit Flips(int num_pancakes) : num_pancakes_(num_pancakes) {}
// Top pancake at index 0, convert to position n.
void Append(int i);
typedef std::vector<int>::const_iterator const_iterator;
const_iterator begin() const { return flips_.begin(); }
const_iterator end() const { return flips_.end(); }
private:
int num_pancakes_;
std::vector<int> flips_;
};
class PositionMap {
public:
// Work on copy of stack, not the original one.
explicit PositionMap(PancakeStack stack);
int pos(int diameter) const;
private:
int num_pancakes_;
int positions_[MAX_DIAMETER];
};
// Work on copy of stack, not the original one.
void Solve(PancakeStack stack, Flips* flips) {
PositionMap pos_map(stack);
while (1) {
int i_max = -1, d_max = -1;
for (int i = 0; i < stack.num_pancakes(); i++) {
int d = stack.diameter(i);
if (pos_map.pos(d) != i && d > d_max) {
i_max = i;
d_max = d;
}
}
if (i_max == -1)
break;
if (i_max > 0) {
stack.Flip(i_max);
flips->Append(i_max);
}
stack.Flip(pos_map.pos(d_max));
flips->Append(pos_map.pos(d_max));
}
}
int main() {
PancakeStack stack;
while (std::cin >> stack) {
Flips flips(stack.num_pancakes());
Solve(stack, &flips);
std::cout << stack << std::endl;
for (Flips::const_iterator i = flips.begin(); i != flips.end(); ++i)
std::cout << *i << ' ';
std::cout << 0 << std::endl;
}
return 0;
}
std::istream& operator>>(std::istream& in, PancakeStack& stack) {
std::string line;
stack.pancakes_.clear();
if (std::getline(in, line)) {
std::stringstream sin(line);
int diameter;
while (sin >> diameter) {
assert(1 <= diameter && diameter <= MAX_DIAMETER);
stack.pancakes_.push_back(diameter);
}
}
return in;
}
std::ostream& operator<<(std::ostream& out, const PancakeStack& stack) {
for (PancakeStack::const_iterator b = stack.begin(), i = b; i != stack.end();
++i) {
(i == b ? out : out << ' ') << *i;
}
return out;
}
void Flips::Append(int i) {
assert(0 <= i && i < num_pancakes_);
flips_.push_back(num_pancakes_ - i);
}
PositionMap::PositionMap(PancakeStack stack)
: num_pancakes_(stack.num_pancakes()) {
stack.Sort();
std::fill(positions_, positions_ + MAX_DIAMETER, -1);
for (int i = 0; i < num_pancakes_; i++)
positions_[stack.diameter(i) - 1] = i;
}
int PositionMap::pos(int diameter) const {
assert(1 <= diameter && diameter <= MAX_DIAMETER);
int i = positions_[diameter - 1];
assert(0 <= i && i < num_pancakes_);
return i;
}