1851A - Escalator Conversations - CodeForces Solution

#include <bits/stdc++.h>
#include <string>
typedef long long ll;
using namespace std;

    int parent[200005];
    int Size[200005];
    void make(int v){
        parent[v]=v;
        Size[v]=1;
    }
    int find(int v){
        if(v==parent[v])return v;
        return parent[v]=find(parent[v]);
    }
    void Union(int a,int b){
        a=find(a);
        b=find(b);
        if(a!=b){
            if(Size[a]<Size[b])swap(a,b);
            parent[b]=a;
            Size[a]+=Size[b];
        }
    }
    /*
int mod=1e9+7;
//int mx=31623;
bool isPrime[31623];
vector<int>prime;
void sieve(){
    for (int i = 0; i < 31623; i++) {
        //* code 
        isPrime[i]=true;
    }
    isPrime[0]=false;
    isPrime[1]=false;
    for (int i = 2; i*i < 31623; i++) {
        code
        if(isPrime[i]){
            for(int j=i*i;j<31623;j+=i){
                isPrime[j]=false;
            }
        }
    }
    for(int i=2;i<31623;i++){
        if(isPrime[i]){
            prime.push_back(i);
        }
    }
}
vector<int> parent;
int find(int x){
    if(parent[x]<0) return x;
    return parent[x]=find(parent[x]);
}
 
bool uni(int u,int v){
    u=find(u);
    v=find(v);
    if(u==v) return true;
    if(parent[u]>parent[v]){
        swap(u,v);
    }
    parent[u]+=parent[v];
    parent[v]=u;
    return false;
}
//int cnst=200000;


bool isPrime(int n)
{
    // Corner cases
    if (n <= 1)
        return false;
  //suppose n=7 that is prime and its pair are (1,7)
  //so if a no. is prime then it can be check by numbers smaller than square root
  // of the n
    for (int i = 2; i * i <= n; i++) {
        if (n % i == 0)
            return false;
    }
    return true;
}
int nCr(int n, int r) {
    // If r is greater than n, return 0
    if (r > n) return 0;
    // If r is 0 or equal to n, return 1
    if (r == 0 || n == r) return 1;
    // Initialize the logarithmic sum to 0
    double res = 0;
    // Calculate the logarithmic sum of the numerator and denominator using loop
    for (int i = 0; i < r; i++) {
        // Add the logarithm of (n-i) and subtract the logarithm of (i+1)
        res += log(n-i) - log(i+1);
    }
    // Convert logarithmic sum back to a normal number
    return (int)round(exp(res));
}*/
//sparse table
/*
const int MAX_N = 100'005;
const int LOG = 17;
int a[MAX_N];
int m[MAX_N][LOG]; // m[i][j] is minimum among a[i..i+2^j-1]
int bin_log[MAX_N];

int query(int L, int R) { // O(1)
	int length = R - L + 1;
	int k = bin_log[length];
	return min(m[L][k], m[R-(1<<k)+1][k]);
}


to write in main

int n;
	cin >> n;
	bin_log[1] = 0;
	for(int i = 2; i <= n; i++) {
		bin_log[i] = bin_log[i/2]+1;
	}
	for(int i = 0; i < n; i++) {
		cin >> a[i];
		m[i][0] = a[i];
	}
	// 2) preprocessing, O(N*log(N))
	for(int k = 1; k < LOG; k++) {
		for(int i = 0; i + (1 << k) - 1 < n; i++) {
			m[i][k] = min(m[i][k-1], m[i+(1<<(k-1))][k-1]);
		}
	}
	// 3) answer queries
	int q;
	cin >> q;
	for(int i = 0; i < q; i++) {
		int L, R;
		cin >> L >> R;
		cout << query(L, R) << "\n";
	}
*/
/*
struct node{
   node* child[2];
   int value;
   node(){
       child[0]=NULL;
       child[1]=NULL;
       value=0;
   }
};
class trie{
   public:
   node* root;
   trie(){
       root= new node;
   }
   void insert(int num){
       node* temp=root;
       for(int i=31;i>=0;i--){
           bool bit=num&(1<<i);
           if(temp->child[bit]==NULL){
               temp->child[bit]=new node;
           }
           temp=temp->child[bit];
       }
       temp->value=num;
   }
   int query(int num){
       node* temp=root;
       for(int i=31;i>=0;i--){
           bool bit=num&(1<<i);
           if(temp->child[1-bit]!=NULL){
               temp=temp->child[1-bit];
           }else if(temp->child[bit]!=NULL){
               temp=temp->child[bit];
           }
       }
       return (temp->value)^num;
   }
};*/
// int helper(int n,int k,int l,int sl){
//     if(k==0 && n>=0)return 1;
//     if(n<0)return 1;
//     int ans=0;
//     for(int i=0;i<=n;i++){
//         ans+=helper(n-i,k--,)
//     }
// }
bool isPrime(int n)
{
    // Corner cases
    if (n <= 1)
        return false;
  //suppose n=7 that is prime and its pair are (1,7)
  //so if a no. is prime then it can be check by numbers smaller than square root
  // of the n
    for (int i = 2; i * i <= n; i++) {
        if (n % i == 0)
            return false;
    }
    return true;
}

int main()
{   
    ios::sync_with_stdio(0);
    cin.tie(0);
	int t;
    cin>>t;
    // t=1;
    while(t--){
        int n,m,k,h;
        cin>>n>>m>>k>>h;
        int a[n];
        int ans=0;
        for(int i=0;i<n;i++)cin>>a[i];
        for(int i=0;i<n;i++){
            int t=abs(a[i]-h);
            if(t%k!=0 || t/k==0)continue;
            if(t/k<m)ans++;
        }
        cout<<ans<<endl;
    }
    return 0;
}