Submission #467034

#	Time	Username	Problem	Language	Result	Execution time	Memory
467034		jazzup	Arranging Shoes (IOI19_shoes)	C++14	0 / 100	8 ms	9944 KiB

shoes

#include "shoes.h"

int Fenwick[200010];
void add(int a,int b){
	for(int i=a;i<=200000;i+=(i&(-i))){
		Fenwick[i]+=b;
	}
}

int query(int a,int b){
	if(a!=0){
		return query(0,b)-query(0,a);
	}

	int ret=0;
	for(int i=b;i>0;i-=(i&(-i))){
		ret+=Fenwick[i];
	}
	return ret;
}

std::vector<std::pair<int,int> > p;
std::vector<int> v[200010];

long long count_swaps(std::vector<int> s) {
	int n=s.size();
	s.insert(s.begin(),0);

	for(int i=1;i<=n;i++){
		if(!v[n-s[i]].empty()){
			p.push_back(std::make_pair(v[n-s[i]].back(),i));
			v[n-s[i]].pop_back();
		}
		else{
			v[n-s[i]].push_back(i);
		}
	}

	// printf("PRE Fenwick\n");

	for(int i=1;i<=n;i++){
		add(i,1);
	}

	// printf("Initialized Fenwick\n");

	long long ans=0;

	for(int i=0;i<p.size()-1;i++){
		ans+=query(p[i].first,p[i].second);
		add(p[i].first,-1);
		add(p[i].second,-1);
	}

	return ans;
}

Compilation message (stderr)

shoes.cpp: In function 'long long int count_swaps(std::vector<int>)':
shoes.cpp:49:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   49 |  for(int i=0;i<p.size()-1;i++){
      |              ~^~~~~~~~~~~

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