Submission #2659634

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Source Code Expand

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

template<typename T> 
struct BIT{
  Int n;
  vector<T> bit;
  //1-indexed
  BIT():n(-1){}
  BIT(Int n_,T d):n(n_),bit(n_+1,d){}
  
  T sum(Int i){
    T s=bit[0];
    for(Int x=i;x<=n;x+=(x&-x))
      s+=bit[x];
    return s;
  }
  void add(Int i,T a){
    if(i==0) return;
    for(Int x=i;x>0;x-=(x&-x))
      bit[x]+=a;
  }
  
  Int lower_bound(Int w){
    if(w<=0) return 0;
    Int x=0,r=1;
    while(r<n) r<<=1;
    for(Int k=r;k>0;k>>=1){
      if(x+k<=n&&bit[x+k]<w){
	w-=bit[x+k];
	x+=k;
      }
    }
    return x+1;
  }
  
  T sum0(Int i){
    return sum(i+1);
  }
  void add0(Int i,T a){
    add(i+1,a);
  }

  T query(Int l,Int r){
    return sum(r-1)-sum(l-1);
  }

  T query0(Int l,Int r){
    return sum(r)-sum(l);
  }
};

//INSERT ABOVE HERE
signed main(){
  Int n;
  cin>>n;
  vector<Int> h(n);
  for(Int i=0;i<n;i++) cin>>h[i];
  vector<Int> v(h);
  sort(v.begin(),v.end());
  v.erase(unique(v.begin(),v.end()),v.end());
  if((Int)v.size()<n){
    cout<<-1<<endl;
    return 0;
  }
  map<Int, Int> m;
  for(Int i=0;i<n;i++) m[v[i]]=i;
  BIT<Int> bit(n+100,0);
  Int ans=0;
  for(Int i=0;i<n;i++){
    ans+=bit.sum0(m[h[i]]+1)*h[i];
    bit.add0(m[h[i]],1);
  }
  cout<<ans<<endl;
  return 0;
}

Submission Info

Judge Result