Submission #259778

#	Time	Username	Problem	Language	Result	Execution time	Memory
259778		youssefbou62	Arranging Shoes (IOI19_shoes)	C++14	50 / 100	1086 ms	18808 KiB

shoes

#include <bits/stdc++.h>
#include "shoes.h"
#define ll long long 
#define pb push_back
#define sz(x) (int)x.size()
#define all(x) x.begin(),x.end()
using namespace std; 
 
const int MAXN = 2e5+5 ; 
vector<int> posR[MAXN],posL[MAXN] ; 
long long count_swaps(std::vector<int> s) {
	ll ans = 0; 
	int n = sz(s)/2 ; 
	for(int i=0;i<sz(s);i++ ){
		int a = s[i] ; 
		if( a > 0 )posR[a].pb(i);
		else posL[-a].pb(i) ;
	}
	for(int i = 1 ; i <= n ; i++ ){
		reverse(all(posR[i]));
		reverse(all(posL[i])); 
	}
	for(int i = 0 ; i < n ; i++ ){
		int l = i * 2 , r = i*2 + 1 ; 
		int bestL , bestR , toadd = 1e9 , bestS = -1; 
		for(int j = 1 ; j <= n ; j++ ){
			while ( !posL[j].empty() && l > posL[j].back() )posL[j].pop_back(); 
			if( posL[j].empty() )continue ; 
			int currL = posL[j].back();
			while ( !posR[j].empty() ){
				if( posR[j].back() < currL && posR[j].back() < l )posR[j].pop_back(); 
				else break ; 
			}
			int currR = posR[j].back(); 
			if( currR < currL )
				currR ++ ; 
			// cout << currL << " " << currR << " " <<  currL + currR - l - r << endl; 
			if( currL + currR - l - r <= toadd)
				bestR = currR , bestL = currL , toadd = currL + currR - l - r ,bestS = j; 
		}
		posR[bestS].pop_back(); 
		posL[bestS].pop_back(); 
		for(int j = 1 ; j <= n ; j++ ){
			for(int& x : posL[j]){
				if( bestL > x )x++; 
				if( bestR > x )x++ ; 
			}
			sort(all(posL[j])); 
			reverse(all(posL[j])); 
			for(int& x : posR[j]){
				if( bestL > x )x++; 
				if( bestR > x )x++ ;
			}
			sort(all(posR[j])); 
			reverse(all(posR[j])); 
		}
		// cout << "for i = "<<i << endl; 
		// cout << bestL << " " << bestR << " " <<toadd<< endl; 
 
		ans += 1LL*toadd ; 
 
	}
	return ans;
}

Compilation message (stderr)

shoes.cpp: In function 'long long int count_swaps(std::vector<int>)':
shoes.cpp:46:5: warning: 'bestR' may be used uninitialized in this function [-Wmaybe-uninitialized]
     if( bestR > x )x++ ; 
     ^~
shoes.cpp:45:5: warning: 'bestL' may be used uninitialized in this function [-Wmaybe-uninitialized]
     if( bestL > x )x++; 
     ^~

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