Submission #3240184

---

Source Code Expand

#include<iostream>
#include<vector>
#include<algorithm>
#include<functional>
#include<queue>
#include<stack>
#include<set>
#include<map>
#include<unordered_map>
#include<climits>
#include<cstdlib>
#include<cmath>
#include<string>
#include<iomanip>

using namespace std;

#define INF 1 << 29
#define LL long long int

LL const MOD = 1000000007;

template<typename T>
class SegmentTree{
    int n;
    int realsize;
    T initialvalue;
    vector<T> tree;

    public:
    
    SegmentTree(int size,T initial):realsize(size),initialvalue(initial){
        n = 1;
        while(n < size)n *= 2;

        tree = vector<T>(2*n + 1,initial);
    }

    //1-indexed
    void insert(int i,T data){
        int ind = n+i-1;
        tree[ind] = data;
        ind >>= 1;
        while(ind > 0){
            tree[ind] = tree[ind*2] + tree[ind*2+1];
            ind >>= 1;
        }
    }

    void add(int i,T data){
        int ind = n+i-1;
        tree[ind] += data;
        ind >>= 1;
        while(ind > 0){
            tree[ind] = tree[ind*2] + tree[ind*2+1];
            ind >>= 1;
        }
    }

    T get(int l,int r){
        if(l > realsize || r > realsize || l <= 0 || r <= 0)return initialvalue;
        l = n+l-1;
        r = n+r-1;
        if(l == r)return tree[l];
        int prel = l;
        int prer = r;
        T lnum = tree[l];
        T rnum = tree[r];
        l >>= 1;
        r >>= 1;
        while(l != r){
            if(l*2 == prel){
                lnum += tree[l*2+1];
            }
            if(r*2+1 == prer){
                rnum += tree[r*2];
            }
            prel = l;
            prer = r;
            l >>= 1;
            r >>= 1;
        }
        return lnum+rnum;
    }
};

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    LL n,k;
    cin >> n >> k;
    vector<LL> a(n+1);
    for(LL i = 1; i < n+1; i++){
        cin >> a[i];
    }

    vector<LL> sum(n+1,0);
    for(LL i = 1; i < n+1; i++){
        sum[i] += sum[i-1] + a[i] - k;
    }

    vector<LL> cpy = sum;
    sort(sum.begin(),sum.end());

    SegmentTree<LL> st(sum.size(),0);
    st.add(lower_bound(sum.begin(),sum.end(),0) - sum.begin() + 1,1);
    
    LL ans = 0;
    for(LL i = 1; i < n+1; i++){
        auto itr = lower_bound(sum.begin(),sum.end(),cpy[i-1]);
        ans += sum.end() - itr;
        ans -= st.get(itr - sum.begin() + 1,sum.size());

        auto itr2 = lower_bound(sum.begin(),sum.end(),cpy[i]);
        st.add(itr2 - sum.begin() + 1,1);
    }

    cout << ans << endl;
    
    return 0;
}

Submission Info

Judge Result