Submission #739422

#	Time	Username	Problem	Language	Result	Execution time	Memory
739422		onebit1024	Data Transfer (IOI19_transfer)	C++17	100 / 100	169 ms	2504 KiB

transfer

#include "transfer.h"
#include <bits/stdc++.h>
using namespace std;
#define pb push_back
 
\
string bin(int x){
	string res;
	for(int i = 30;i>=0;--i){
		if(x&(1ll<<i))res+='1';
		else res+='0';
	}
	while(!res.empty() && res[0]=='0')res.erase(res.begin());
	return res;
}
int power(int x){
	// is x a power of 2
	while((x%2)==0)x/=2;
	if(x==1)return 1;
	return 0;
}
 
 
std::vector<int> get_attachment(std::vector<int> source) {
	int v = 3;
	int x = 0;
	for(int i = 0;i<source.size();++i){
		while(power(v))v++;
		if(source[i])x^=v;
		v++;
	}
	string s= bin(x);
	vector<int>ret;
	for(auto w : s)ret.pb(w-'0');
	return ret;
}

std::vector<int> retrieve(std::vector<int> data) {
	int N = 63;
	if(data.size()>100)N = 255;
 
	int bits = data.size()-N;
	vector<int>ret;

	int v = 3, X = 0, Y = 0;
	for(int i = 0;i<N;++i){
		while(power(v))v++;
		if(data[i])X^=v;
		v++;
	}
	
	int pos = 0;
	for(int i = data.size()-1;i>=N;--i){
		if(data[i])Y+=(1ll<<pos);
		pos++;
	}
	if(X==Y){
		for(int i = 0;i<N;++i)ret.pb(data[i]);
		return ret;
	}
	v = 3;
	for(int i = 0;i<N;++i){
		while(power(v))v++;
		int nsum = X;
		data[i] = 1-data[i];
		nsum^=v;
		data[i] = 1-data[i];
		if(nsum==Y){
			for(int j = 0;j<i;++j)ret.pb(data[j]);
			ret.pb((data[i]?0:1));
			for(int j = i+1;j<N;++j)ret.pb(data[j]);
			return ret;
		}
		v++;
	}
	for(int i = 0;i<N;++i)ret.pb(data[i]);
	return ret;
}

Compilation message (stderr)

transfer.cpp: In function 'std::vector<int> get_attachment(std::vector<int>)':
transfer.cpp:27:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   27 |  for(int i = 0;i<source.size();++i){
      |                ~^~~~~~~~~~~~~~
transfer.cpp: In function 'std::vector<int> retrieve(std::vector<int>)':
transfer.cpp:42:6: warning: unused variable 'bits' [-Wunused-variable]
   42 |  int bits = data.size()-N;
      |      ^~~~

• Subtask 1: 60 / 60
• Subtask 2: 40 / 40