Submission #1022653

#	Time	Username	Problem	Language	Result	Execution time	Memory
1022653		CodeAssignment	Arranging Shoes (IOI19_shoes)	C++17	50 / 100	1100 ms	14104 KiB

shoes

#include <bits/stdc++.h>
using namespace std;

#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
#define trav(a, x) for (auto &a : x)
#define pb push_back
#define el "\n";
#define dbg(x) cerr << "\e[92m" << #x << " = " << x << "\e[97m" << el;
//#define dbg(x)  
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;

/* dies on 
4
1 2 1 -1 -2 -1 3 -3
*/

ll count_swaps(vector<int> S) {
	assert(sz(S) % 2 == 0);
	ll n = sz(S) / 2; // number of pairs
	vi a = S;

	vector<vll> pos(2 * n + 1);
	rep(i, 0, 2*n) {
		dbg(i);
		pos[a[i] + n].pb(i);
		dbg(a[i]);
	}
	ll ans = 0;
	ll ind = 0;
	while(ind < 2 * n) {
		ll cur = a[ind];
		auto nxt = upper_bound(all(pos[-cur + n]), ind);
		auto dbgarray = [&](vi &arr, string s) -> void {
			cerr << s << " is: ";
			rep(i, 0, sz(arr)) {
				cerr << arr[i] << " ";
			}
			cerr << el;
		};
		//dbgarray(a, "a");

		assert(nxt != pos[-cur + n].end());
		assert(a[*nxt] == -cur);

		vi temp;
		rep(i, 0, ind) {
			temp.pb(a[i]);
		}
		//dbgarray(temp, "temp");
		temp.pb((cur < 0 ? cur : -cur));
		temp.pb((cur < 0 ? -cur : cur));
		//dbgarray(temp, "temp");
		rep(i, ind + 1, 2*n)  {
			if (i == *nxt) continue;
			temp.pb(a[i]);
		}
		//dbgarray(temp, "temp");
		ans += (*nxt) - ind - (cur < 0 ? 1 : 0);
		assert(sz(temp) == 2 * n);
		ind += 2;

		swap(a, temp);
		pos.assign(2 * n + 1, vll());
		rep(i, 0, 2*n) {
			pos[a[i] + n].pb(i);
		}
	}
	return ans;
}

Compilation message (stderr)

shoes.cpp: In function 'll count_swaps(std::vector<int>)':
shoes.cpp:38:8: warning: variable 'dbgarray' set but not used [-Wunused-but-set-variable]
   38 |   auto dbgarray = [&](vi &arr, string s) -> void {
      |        ^~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 20 / 20
• Subtask 3: 0 / 20
• Subtask 4: 0 / 15
• Subtask 5: 20 / 20
• Subtask 6: 0 / 15