HackerRank Non Divisible Subset Solution

#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>
int main(){
    int n; 
    int k; 
    scanf("%d %d",&n,&k);
    
    int count[k];
    for (int i = 0; i < k; i++) {
        count[i] = 0;
    }
    
    for(int i = 0; i < n; i++){
        int a;
        scanf("%d",&a);
        count[a % k]++;
    }
    
    int max = 0;
    for (int i = 0; i <= k/2; i++) {
        if (i == 0 || i == k - i) {
            if (count[i] >= 1) {
                max += 1;
            }
        } else {
            max += count[i] > count[k-i] ? count[i] : count[k-i];
        }
    }
    printf("%d\n",max);
    
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i = (a); i <= (b); ++i)
#define FORD(i,a,b) for(int i = (a); i >= (b); --i)
#define RI(i,n) FOR(i,1,(n))
#define REP(i,n) FOR(i,0,(n)-1)
#define mini(a,b) a=min(a,b)
#define maxi(a,b) a=max(a,b)
#define mp make_pair
#define pb push_back
#define st first
#define nd second
#define sz(w) (int) w.size()
typedef vector<int> vi;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
const int inf = 1e9 + 5;
const int nax = 1e6 + 5;
int t[nax];
int main() {
	
	int n, k;
	scanf("%d%d", &n, &k);
	REP(_, n) {
		int a;
		scanf("%d", &a);
		++t[a%k];
	}
	int s = 0;
	s += min(t[0], 1);
	RI(i, k-1) {
		int j = k-i;
		if(j < i) break;
		if(i == j) s+= min(t[i], 1);
		else s += max(t[i], t[j]);
	}
	printf("%d\n", s);
	
	return 0;
}

import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;
public class Solution {
    public static void main(String[] args) throws IOException{
        new Solution().run();
    }
    
    public void run() throws IOException{
        Scanner in = new Scanner(System.in);
        BufferedWriter log = new BufferedWriter(new OutputStreamWriter(System.out));
        int n = in.nextInt();
        int k = in.nextInt();
        
        int[]a = new int[n];
        int[]c = new int[k];
        
        for(int i=0;i<n;i++){
            a[i] = in.nextInt();
            a[i]=a[i]%k;
            c[a[i]]++;
        }
        
        int ans=0;
        ans+=(c[0]>0)?1:0;//good if 1 exists, cannot be more
        for(int i=1;i<=k-i;i++){
            if(i<k-i) {
                ans+=Math.max(c[i],c[k-i]);
            } else {//i==k-i
                ans+=(c[i]>0)?1:0;//not more possible
            }
        }
        log.write("" +ans+"\n"); 
        
        log.flush();
    }
}

rr = raw_input
rrM = lambda: map(int,rr().split())
N,K = rrM()
A = rrM()
S = [0 for _ in xrange(K)]
for i in A: S[i%K] += 1
ans = 0
for p in xrange(K/2 + 1):
    q = (K-p)%K
    if p==q: ans += 1 if S[p] else 0
    else: ans += max(S[p],S[q])
print ans

function processData(input) {
    //Enter your code here
    var lines = input.split(/[\r\n]+/);
    var n_k = lines[0].split(' ').map(Number);
    var n = n_k[0], k = n_k[1];
    var ar = lines[1].split(' ').map(Number);
    
    var o = {};
    for(var i = 0; i < ar.length; i++) {
        var r = ar[i] % k;
        o[r] = o[r] ? o[r] + 1 : 1;
    }
    
    var c = 0;
    for(var key in o) {
        var f = parseInt(key);
        
        if (f == 0) {
            if (o[f] >= 1) { c++; }
        }
        else {
            var f2 = k - f;
            if (f > f2 && o[f2]) { continue; }
            else if (f == f2) {
                if (o[f] >= 1) { c++; }
            }
            else {
                var a = o[f] || 0;
                var b = o[f2] || 0;
                c += Math.max(a, b);
            }
        }
    }
    
    console.log(c);
} 
process.stdin.resume();
process.stdin.setEncoding("ascii");
_input = "";
process.stdin.on("data", function (input) {
    _input += input;
});
process.stdin.on("end", function () {
   processData(_input);
});

object Solution {
    def main(args: Array[String]) {
     val sc = new java.util.Scanner(System.in)
    //val sc = new Scanner(new File("/home/maxim/hackerrank/nondiv.txt"))
    val n = sc.nextInt()
    val k = sc.nextInt()
    var values = new Array[Int](k)
    for (i <- 0 until n) {
      values(sc.nextInt()%k) += 1
    }
    var maxCount = if (values(0) > 0) 1 else 0
    if ((k % 2 == 0) && (values(k/2) >0)) maxCount += 1
    for (i <- 1 until k / 2  + k % 2) {
      if (values(i) > values(k-i)) {
        maxCount += values(i)
      } else {
        maxCount += values(k - i)
      }
    }
    println (maxCount)
    }
}

var
    i,n,k,t,x:longint;
    a : array[0..101] of longint;
begin
    readln(n,k);
    for i:=1 to n do
    begin
        read(x);
        a[x mod k]:=a[x mod k]+1;
    end;
    if a[0]>0 then t:=1 else t:=0;
    for i:=1 to (k-1) div 2 do
    if (a[i]>a[k-i]) then t:=t+a[i] else t:=t+a[k-i];
    if (k mod 2=0) and (a[k div 2]>0) then t:=t+1;
    writeln(t);
end.