Submission #246392

#	Time	Username	Problem	Language	Result	Execution time	Memory
246392		luisoncpp	Parrots (IOI11_parrots)	C++17	98 / 100	18 ms	1792 KiB

encoder

#include <algorithm>
#include <iostream>
#include <vector>
#include <cstdint>
#include <cstdlib>
#include <cassert>
#include <queue>
#include <unordered_map>
#define PARROTS
#ifndef PARROTS_MAIN
#include "encoder.h"
#include "encoderlib.h"
#endif

template<typename T>
using Vec = std::vector<T>;

Vec<int> SplitInto2Bit(int N, int* message) {
	Vec<int> ret;
	for (int i = 0; i < N; ++i) {
		for (int k = 0; k < 4; ++k) {
			int a = (message[i]>>(2*k));
			ret.push_back(a&3);
		}
	}
	return ret;
}

Vec<int> MoreFrequentWord(const Vec<int>& vec) {
	Vec<std::pair<int, int>> count_and_val{std::make_pair(0, 0), std::make_pair(0, 1), std::make_pair(0, 2), std::make_pair(0, 3)};
	for (int num : vec) {
		++count_and_val[num].first;
	}
	std::sort(count_and_val.begin(), count_and_val.end());
	std::reverse(count_and_val.begin(), count_and_val.end());
	int num = count_and_val[0].second + count_and_val[1].second*4 + count_and_val[2].second*16 + count_and_val[3].second*64;
	if (count_and_val[0].first != count_and_val[1].first || count_and_val[0].first != count_and_val[2].first || count_and_val[0].first != count_and_val[3].first) {
		for (int i = 0; i < 4; ++i) {
			send(num);
		}
	} else {
		return {0, 1, 2, 3};
	}
	return {count_and_val[0].second, count_and_val[1].second, count_and_val[2].second, count_and_val[3].second};
}

void encode(int N, int* message_8) {
	auto message = SplitInto2Bit(N, message_8);
	auto frequency = MoreFrequentWord(message);
	Vec<int> inverse_f(4);
	for (int i = 0; i < frequency.size(); ++i) {
		inverse_f[frequency[i]] = i;
	}
	for (int i = 0; i < message.size(); ++i) {
		int num = message[i];
		assert(num>=0 && num<4);
		int times = inverse_f[num];
		while (times--) {
			send(i);
		}
	}
}

decoder

#include <algorithm>
#include <iostream>
#include <vector>
#include <cstdint>
#include <cstdlib>
#include <cassert>
#include <queue>
#include <unordered_map>
#ifndef PARROTS_MAIN
#include "decoder.h"
#include "decoderlib.h"
#endif
#ifndef PARROTS
template<typename T>
using Vec = std::vector<T>;
#endif

Vec<int> decodeTransition(int order) {
	Vec<int> trans(4);
	for (int k = 0; k < 4; ++k) {
		trans[k] = ((order>>(2*k))&3);
	}
	return trans;
}
void substituteWithTransition(const Vec<int>& trans, Vec<int>& decoded_2_bit) {
	for (int& num : decoded_2_bit) {
		num = trans[num];
	}
}
void outputFrom2BitVector(const Vec<int>& vec) {
	for (int i = 0; i < vec.size(); i += 4) {
		int num = 0;
		for (int k = 0; k < 4; ++k) {
			int x = vec.at(i + k);
			num |= (x<<(2*k));
		}
		output(num);
	}
}

void decode(int N, int L, int* X) {
	Vec<int> decoded_2_bit(4*N);
	std::unordered_map<int, int> Count;
	int order = 0 + 1*4 + 2*16 + 3*64;
	for (int i = 0; i < L; ++i) {
		++Count[X[i]];
		if (Count[X[i]] >= 4) {
			order = X[i];
			Count[X[i]] -= 4;
		}
	}
	for (auto item : Count) {
		if (item.second > 0) {
			decoded_2_bit.at(item.first) = item.second;
		}
	}
	Vec<int> trans = decodeTransition(order);
	substituteWithTransition(trans, decoded_2_bit);
	outputFrom2BitVector(decoded_2_bit);
}

Compilation message (stderr)

encoder.cpp: In function 'void encode(int, int*)':
encoder.cpp:51:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < frequency.size(); ++i) {
                  ~~^~~~~~~~~~~~~~~~~~
encoder.cpp:54:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < message.size(); ++i) {
                  ~~^~~~~~~~~~~~~~~~

decoder.cpp: In function 'void outputFrom2BitVector(Vec<int>&)':
decoder.cpp:31:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < vec.size(); i += 4) {
                  ~~^~~~~~~~~~~~

• Subtask 1: 17 / 17
• Subtask 2: 17 / 17
• Subtask 3: 18 / 18
• Subtask 4: 29 / 29
• Subtask 5: 17 / 19