Submission #91178

#	Time	Username	Problem	Language	Result	Execution time	Memory
91178		emil_physmath	Bootfall (IZhO17_bootfall)	C++14	6 / 100	1037 ms	123240 KiB

bootfall

#include <iostream>
#include <stdio.h>
#include <unordered_set>
#include <cstring>
#include <vector>
#include <cmath>
#include <set>
using namespace std;
const int MAXN=500, MAXSUM=500*500;

int a[MAXN+1];
bool dp[MAXN][MAXSUM+1];

vector<int> AllPossSums(int arr[], int n);
int main()
{
	int n, sum=0;
	cin>>n;
	set<int> mods;
	for (int i=0; i<n; i++)
	{
		scanf("%d", a+i);
		mods.insert(a[i]%2);
		sum+=a[i];
	}
	if (mods.size()>1)
	{
		cout<<"0\n";
		return 0;
	}
	if (*(mods.begin()))
		if (n%2)
		{
			cout<<"0\n";
			return 0;
		}
	vector<int> curSums;
	curSums=AllPossSums(a, n);
	bool f=false;
	for (int i=0; i<curSums.size(); i++)
		if (curSums[i]*2==sum)
		{
			f=true;
			break;
		}
	if (!f)
	{
		cout<<"0\n";
		return 0;
	}
	unordered_set<int> ans;
	for (int i=0; i<n; i++)
	{ // #i doesn't play.
		sum-=a[i];
		swap(a[i], a[n-1]);
		curSums=AllPossSums(a, n-1);
		unordered_set<int> curAns;
		for (int j=0; j<curSums.size(); j++)
			curAns.insert(abs((sum-curSums[j])-curSums[j]));
		if (!i)
		{
			ans=curAns;
			swap(a[i], a[n-1]);
			sum+=a[i];
			continue;
		}
		unordered_set<int> temp;
		for (auto it=curAns.begin(); it!=curAns.end(); it++)
			if (ans.find(*it)!=ans.end())
			{
				temp.insert(*it);
				ans.erase(*it);
				//curAns.erase(*it);
			}
		ans=temp;
		swap(a[i], a[n-1]);
		sum+=a[i];
	}
	cout<<ans.size()<<'\n';
	set<int> ansOut(ans.begin(), ans.end());
	for (auto it=ansOut.begin(); it!=ansOut.end(); it++)
		cout<<*it<<' ';
	cout<<endl;

	char I;
	cin >> I;
	return 0;
}

vector<int> AllPossSums(int arr[], int n)
{
	int sum=0;
	for (int i=0; i<n; i++)
		sum+=arr[i];
	memset(dp, 0, sizeof(dp));
	for (int i=0; i<=n; i++)
		dp[i][0]=true;
	for (int i=1; i<=n; i++)
	{
		dp[i][arr[i-1]]=true;
		for (int j=1; j<=sum; j++)
		{
			if (dp[i-1][j]==true)
			{
				dp[i][j]=true;
				dp[i][j+arr[i-1]]=true;
			}
		}
	}
	vector<int> res;
	for (int j=0; j<=sum; j++)
		if (dp[n][j]==true)
			res.push_back(j);
	return res;
}

Compilation message (stderr)

bootfall.cpp: In function 'int main()':
bootfall.cpp:40:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i=0; i<curSums.size(); i++)
                ~^~~~~~~~~~~~~~~
bootfall.cpp:58:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j=0; j<curSums.size(); j++)
                 ~^~~~~~~~~~~~~~~
bootfall.cpp:22:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", a+i);
   ~~~~~^~~~~~~~~~~

• Subtask 1: 6 / 6
• Subtask 2: 0 / 7
• Subtask 3: 0 / 15
• Subtask 4: 0 / 16
• Subtask 5: 0 / 21
• Subtask 6: 0 / 35