Submission #467379

#	Time	Username	Problem	Language	Result	Execution time	Memory
467379		ChrisGe123	Arranging Shoes (IOI19_shoes)	C++14	Compilation error	0 ms	0 KiB

shoes

#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
// #include <ext/pb_ds/tree_policy.hpp>
// #include <ext/pb_ds/assoc_container.hpp>
// using namespace __gnu_pbds;
// template <class T> using Tree = tree<T, null_type, less<T>,
//     rb_tree_tag, tree_order_statistics_node_update>;

const int maxn = 100002;
#define mp make_pair
#define pb push_back
#define f first
#define s second

const int mod = 1e9+7;

typedef pair<int, int> pii;
int n;

int shoes[2*maxn];
// for each shoe, we need the closest shoe to the right that is the opposite pair to it
int r[2*maxn];
vector<int> eachsize[2*maxn]; //eachsize[i] contains the positions of the shoes of size i-n in order
int sizepos[2*maxn]; //sizepos[i] tells us how many shoes of size i-n we've seen 
int fentree[2*maxn];

/*
We need to figure out using some PURS thing how to get the number of elements between i and r[i] that have already been taken care of
we can do this by just making a BIT where initially everything is 1, and then if the element i has been used, we make BIT[i] = 0


*/
int lsb(int a)
{
	return a & -a;
}
void change(int a, int c)
{
	while (a <= 2*n)
	{
		fentree[a] += c;
		a += lsb(a);
	}
}
int sum(int a)
{
	int s = 0;
	while (a > 0)
	{
		s += fentree[a];
		a -= lsb(a);
	}
	return s;
}
void setupIO(string s)
{
	freopen((s + ".in").c_str(), "r", stdin);
	freopen((s + ".out").c_str(), "w", stdout);
}

int main()
{
	//setupIO("arrangeshoes");
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cin >> n;
	for (int i=1; i<=2*n; i++)
	{
		cin >> shoes[i];
		eachsize[shoes[i]+n].pb(i);
	}
	for (int i=1; i<=2*n; i++)
	{
		if (sizepos[shoes[i]+n] < (int) eachsize[-shoes[i]+n].size())
		{
			int temp = eachsize[-shoes[i]+n][sizepos[shoes[i]+n]];
			if (temp > i)
			{
				r[i] = temp;
			}
		}
		sizepos[shoes[i]+n]++;
	}

	ll ans = 0;
	for (int i=1; i<=2*n; i++)
	{
		change(i, 1);
	}
	for (int i=1; i<=2*n; i++)
	{
		if (r[i] != 0)
		{
			if (r[i] != i+1)
			{
				ans += sum(r[i]-1) - sum(i);
				//cerr << sum(r[i]-1) << " " << sum(i) << endl;
			}
			if (shoes[i] > 0)
			{
				ans++;
			}
			change(r[i], -1);
		}
	}
	cout << ans << endl;
}

Compilation message (stderr)

shoes.cpp: In function 'void setupIO(std::string)':
shoes.cpp:58:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   58 |  freopen((s + ".in").c_str(), "r", stdin);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
shoes.cpp:59:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   59 |  freopen((s + ".out").c_str(), "w", stdout);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/bin/ld: /tmp/ccG8AA4u.o: in function `main':
grader.cpp:(.text.startup+0x0): multiple definition of `main'; /tmp/cc37ttIx.o:shoes.cpp:(.text.startup+0x0): first defined here
/usr/bin/ld: /tmp/ccG8AA4u.o: in function `main':
grader.cpp:(.text.startup+0x29d): undefined reference to `count_swaps(std::vector<int, std::allocator<int> >)'
collect2: error: ld returned 1 exit status