Source Code
#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <ctype.h>
#include <queue>
#include <cstring>
#include <set>
#include <bitset>
#include <map>
#include <chrono>
#include <random>
#include <unordered_map>
#include <stdio.h>
#include <deque>
#include <iomanip>
#include <stack>
#include <cassert>
using namespace std;
using ll = long long;
#define int long long
#define pb push_back
#define ff first
#define ss second
#define all(x) (x).begin(), (x).end()
#define ain(x,n) for(int i=0;i<n;i++)cin>>x[i];
#define aout(x,n) for(int i=0;i<n;i++)cout<<x[i]<<" ";
#define pii pair<int,int>
//#define endl '\n'
//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int mod=1e9+7;
bool cmp(pii a,pii b)
{
    if(a.second==b.second)return a.ff>b.ff;
    return a.second<b.second;
}
int power(int x,  int y, int p)
{
    int res = 1;
    x = x % p;
    if (x == 0) return 0;
    while (y > 0)
    {
        if (y & 1)
            res = (res*x) % p;
        y = y>>1;
        x = (x*x) % p;
    }
    return res;
}
void solve(int tccc)
{
    int n,k;
    cin>>n>>k;
    int arr[n+1];
    for(int i=1;i<=n;i++)
    {
        cin>>arr[i];
        arr[i]%=k;
    }
    int pf[n+1]={};
    int anpf[n+1]={};
    map<int,int>freq;
    for(int i=1;i<=n;i++)
    {
        pf[i]=arr[i]+pf[i-1];
        pf[i]%=k;
        if(i!=n)
        freq[pf[i]]++;
    }
    int ans=0;
    int ss=0;
    for(int i=n;i>=1;i--)
    {
        ans+=freq[(0-ss+k+k)%k];
        ss+=arr[i];
        ss%=k;
        freq[pf[i]]--;
    }
    cout<<ans<<endl;

}

int32_t main()
{

    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int t=1;
    cin>>t;
    for(int i=1;i<=t;i++)
    {
        solve(i);
    }

}

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Number of Ways MrPie
GNU G++17
51 ms
304 KB
Wrong Answer