Submission #718805

#	Time	Username	Problem	Language	Result	Execution time	Memory
718805		Yell0	Arranging Shoes (IOI19_shoes)	C++17	10 / 100	23 ms	10184 KiB

shoes

#include <bits/stdc++.h>
 
using namespace std;
const int MN=1e5+2;
typedef long long ll;
typedef pair<int,int> pii;
struct node{int l,r,sum;} seg[4*MN];

void bld(int l,int r,int i) {
  seg[i].l=l;
  seg[i].r=r;
  if(l==r) return;
  int mid=(l+r)/2;
  bld(l,mid,i*2);
  bld(mid+1,r,i*2+1);
  seg[i].sum=0;
}

int qry(int l,int r,int i) {
  if(l==seg[i].l&&r==seg[i].r) return seg[i].sum;
  int mid=(seg[i].l+seg[i].r)/2;
  if(r<=mid) return qry(l,r,i*2);
  else if(l>mid) return qry(l,r,i*2+1);
  else return qry(l,mid,i*2)+qry(mid+1,r,i*2+1);
}

void upd(int p,int v,int i) {
  if(seg[i].l==seg[i].r) {
    seg[i].sum=v;
    return;
  }
  int mid=(seg[i].l+seg[i].r)/2;
  if(p<=mid) upd(p,v,i*2);
  else upd(p,v,i*2+1);
  seg[i].sum=seg[i*2].sum+seg[i*2+1].sum;
}

ll count_swaps(vector<int> S) {
  ll N=S.size()/2,ans=0,sub=0;
  bld(0,N*2-1,1);
  vector<vector<int>> pos(2*N+1);
  for(int i=0;i<2*N;++i) {
    pos[S[i]+N].push_back(i);
    if(S[i]<0) upd(i,-1,1);
    else upd(i,1,1);
  }
  vector<pii> in;
  for(int i=0;i<N;++i)
    for(int j=0;j<pos[i].size();++j) {
      in.push_back(pii(min(pos[i][j],pos[N+N-i][j]),max(pos[i][j],pos[N+N-i][j])));
      ans+=(pos[N+N-i][j]<pos[i][j]);
    }
  for(pii p:in) {
    if(p.second==p.first+1) continue;
    ans+=p.second-p.first-1;
    sub+=abs(qry(p.first+1,p.second-1,1));
  }
  return ans-sub/2;
}

Compilation message (stderr)

shoes.cpp: In function 'll count_swaps(std::vector<int>)':
shoes.cpp:49:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   49 |     for(int j=0;j<pos[i].size();++j) {
      |                 ~^~~~~~~~~~~~~~

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