Submission #35410016

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Source Code Expand

#include <iostream> // cout, endl, cin
#include <string> // string, to_string, stoi
#include <vector> // vector
#include <algorithm> // min, max, swap, sort, reverse, lower_bound, upper_bound
#include <utility> // pair, make_pair
#include <tuple> // tuple, make_tuple
#include <cstdint> // int64_t, int*_t
#include <cstdio> // printf
#include <map> // map
#include <queue> // queue, priority_queue
#include <set> // set
#include <stack> // stack
#include <deque> // deque
#include <unordered_map> // unordered_map
#include <unordered_set> // unordered_set
#include <bitset> // bitset
#include <cctype> // isupper, islower, isdigit, toupper, tolower
#include <iomanip>
#include <climits>
#include <cmath>
#include <functional>
#include <numeric>
#include <regex>
#include <array>
#include <fstream>
#include <sstream>

//#include<atcoder/modint>
//using namespace atcoder;

#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep1(i, n) for (int i = 1; i <= (int)(n); i++)
#define repl(i,l,r) for (int i = l; i < (int)(r); i++)
#define all(a) a.begin(),a.end()
#define Pii pair<int,int>
#define Pll pair<long,long>
#define INFi 1000000001
#define INFl 1000000000000000001
#define ll long long
using namespace std;



template<class T> inline bool chmin(T& a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template<class T> inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

template<class T> void printArray(vector<T>&A){
    for(T&a:A){
        cout<<a<<" ";
    }
    cout<<endl;
}
template<class T> void printArrayln(vector<T>&A){
    for(T&a:A){
        cout<<a<<endl;
    }
}


template<class T1,class T2> std::ostream &operator<<(std::ostream &out, const pair<T1,T2> &A){
    cout<<"{"<<A.first<<","<<A.second<<"}";
    return out;
}

template<class T1,class T2> std::ostream &operator<<(std::ostream &out, const map<T1,T2> &M){
    for(const auto&A:M){
        cout<<"{"<<A.first<<","<<A.second<<"}";
    }
    return out;
}

template<class T1> std::ostream &operator<<(std::ostream &out, const set<T1> &M){
    cout<<"{";
    for(const auto&A:M){
        cout<<A<<", ";
    }
    cout<<"}"<<endl;
    return out;
}


template<class T1> std::ostream &operator<<(std::ostream &out, const multiset<T1> &M){
    cout<<"{";
    for(const auto&A:M){
        cout<<A<<", ";
    }
    cout<<"}"<<endl;
    return out;
}

template<class T> std::ostream &operator<<(std::ostream &out, const vector<T> &A){
    for(const T &a:A){
        cout<<a<<" ";
    }
    return out;
}

void print() { cout << endl; }
 
template <typename Head, typename... Tail>
void print(Head H, Tail... T) {
  cout << H << " ";
  print(T...);
}


template<class T> std::istream &operator>>(std::istream &in,vector<T>&A){
    for(T&a:A){
        std::cin>>a;
    }
    return in;
}

template<typename T>
struct RSQ{
    int n;
    vector<T>dat;
    const T ZERO;
    RSQ(int n_,T ZERO_):ZERO(ZERO_){
        n=1;
        while(n<n_)n*=2;
        //完全二分木にする
        dat.assign(2*n-1,ZERO);
    }
    void update(int k,T a){
        k+=n-1;// i番目は、配列上では n-1+i 番目に格納されている
        dat[k]+=a;// 葉の更新
        while(k>0){
            k=(k-1)/2; //親のインデックス
            // 子の和を計算
            dat[k]=dat[k*2+1]+dat[k*2+2];
        }
    }
    
    T query(int a,int b,int k,int l,int r){
        if(r<=a||b<=l)return ZERO;//範囲外
        if(a<=l&&r<=b)return dat[k]; //範囲内である
        else{
            T vl=query(a,b,k*2+1,l,(l+r)/2);
            T vr=query(a,b,k*2+2,(l+r)/2,r);
            return vl+vr;
        }
    }
    //[a,b)の総和を求める
    T query(int a,int b){
        return query(a,b,0,0,n);
    }
};


int main(void){
    /*転倒数計算*/
    int n;cin>>n;
    vector<int>A(n);
    for(int i=0;i<n;i++){
        cin>>A[i];
        A[i]--;
    }
    RSQ<int>rsq(n,0);
    long ans=0;
    for(int i=0;i<n;i++){
        ans+=rsq.query(A[i]+1,n);
        rsq.update(A[i],1);
    }
    cout<<ans<<endl;
}

Submission Info

Judge Result