Submission #211165

#	Time	Username	Problem	Language	Result	Execution time	Memory
211165		arctan	Arranging Shoes (IOI19_shoes)	C++14	50 / 100	1102 ms	141788 KiB

shoes

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


typedef long long ll;
const ll mod=1e9+7;
const ll maxn=200005;
const ll inf=1e9+7;
queue<ll> m[2][100005];
ll BIT[maxn];
inline int lsb(int x)
{
    return x&(-x);
}
void add(int x,int v)
{
  	for(int i=x;i<maxn;i+=lsb(i))
    {
        BIT[i]+=v;
    }

}
ll query(ll x)
{
    //assert(x>=0);
    ll res=0;
  	int cnt=0;
    for(int i=x;i>0;i-=lsb(i))
    {
        res+=BIT[i];
    }
    return res;
}
ll count_swaps(std::vector<int> s)
{
    for(int i=0;i<s.size();i++)
    {
        bool x=0;
        if(s[i]<0)
        {
            x=1;
            m[x][-s[i]].push(i);
        }
        else m[x][s[i]].push(i);
        add(i+1,1);
    }
    ll sum=0;
    for(int i=0;i<s.size();i++)
    {
        bool x=(s[i]<0);
        s[i]=abs(s[i]);
        queue<ll> q=m[!x][s[i]];
        if(q.empty()) continue;
        if(m[x][s[i]].front()!=i) continue;
        //assert(m[s[i]].size()==m[-s[i]].size());
        ll p=q.front();
        m[x][s[i]].pop();
        m[!x][s[i]].pop();
        sum+=query(p)-query(i+1);
        if(!x) sum++;
        //cout<<i<<" "<<sum<<"\n";
        add(p+1,-1);
        add(i+1,-1);
        //if(i>50000) assert(0);
    }



    return sum;
}

Compilation message (stderr)

shoes.cpp: In function 'll query(ll)':
shoes.cpp:28:8: warning: unused variable 'cnt' [-Wunused-variable]
    int cnt=0;
        ^~~
shoes.cpp: In function 'll count_swaps(std::vector<int>)':
shoes.cpp:37:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<s.size();i++)
                 ~^~~~~~~~~
shoes.cpp:49:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<s.size();i++)
                 ~^~~~~~~~~

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