[2019.02.11] Divisible Sum Pairs

Problem

You are given an array of  integers, , and a positive integer, . Find and print the number of  pairs where  and  +  is divisible by .

For example,  and . Our three pairs meeting the criteria are  and .

Function Description

Complete the divisibleSumPairs function in the editor below. It should return the integer count of pairs meeting the criteria.

divisibleSumPairs has the following parameter(s):

• n: the integer length of array 
• ar: an array of integers
• k: the integer to divide the pair sum by

Input Format

The first line contains  space-separated integers,  and . 
The second line contains  space-separated integers describing the values of .

Constraints

Output Format

Print the number of  pairs where  and  +  is evenly divisible by .

Sample Input

6 3
1 3 2 6 1 2

Sample Output

 5

Explanation

Here are the 5 valid pairs when k = 3:

* (0, 2) → ar[0] + ar[2] = 1 + 2 = 3

* (0, 5) → ar[0] + ar[5] = 1 + 2 = 3

* (1, 3) → ar[1] + ar[3] = 3 + 6 = 9

* (2, 4) → ar[2] + ar[4] = 2 + 1 = 3

* (4, 5) → ar[4] + ar[5] = 1 + 2 = 3

How I solved the problem

# 배열이 연속하는 수가 아니기 때문에 이중 반복문이 돌아야함!

# 같은 배열이 겹치지 않도록 반복문을 짜는게 중요함.

# i가 0이라면 j는 1부터 시작하도록 해서 j가 1보다 항상 크게 시작하도록 짜는 것이 중요

# 나누어질 수 있는 배열의 합의 개수를 리턴해야하기 때문에 나머지 함수 %가 0이 되는 것을 찾기

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59

import java.io.*; import java.math.*; import java.security.*; import java.text.*; import java.util.*; import java.util.concurrent.*; import java.util.regex.*;   public class Solution {       // Complete the divisibleSumPairs function below.     static int divisibleSumPairs(int n, int k, int[] ar) {         int result = 0;           for (int i = 0; i < n; i++) {             for (int j = i + 1; j < n; j++) {//at least, j is bigger than i                 int sum = ar[i] + ar[j]; //sum a pair of ar                   if (sum % k == 0) { //test if the sum is divisible                     result++;                 }             }         }           return result;     }       private static final Scanner scanner = new Scanner(System.in);       public static void main(String[] args) throws IOException {         BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));           String[] nk = scanner.nextLine().split(" ");           int n = Integer.parseInt(nk[0]);           int k = Integer.parseInt(nk[1]);           int[] ar = new int[n];           String[] arItems = scanner.nextLine().split(" ");         scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");           for (int i = 0; i < n; i++) {             int arItem = Integer.parseInt(arItems[i]);             ar[i] = arItem;         }           int result = divisibleSumPairs(n, k, ar);           bufferedWriter.write(String.valueOf(result));         bufferedWriter.newLine();           bufferedWriter.close();           scanner.close();     } }   Colored by Color Scripter

cs

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