Hackerrank Pairs Solution
8 min read

Hackerrank Pairs Solution

Hackerrank Pairs Solution

.MathJax_SVG_Display {text-align: center; margin: 1em 0em; position: relative; display: block!important; text-indent: 0; max-width: none; max-height: none; min-width: 0; min-height: 0; width: 100%} .MathJax_SVG .MJX-monospace {font-family: monospace} .MathJax_SVG .MJX-sans-serif {font-family: sans-serif} .MathJax_SVG {display: inline; font-style: normal; font-weight: normal; line-height: normal; font-size: 100%; font-size-adjust: none; text-indent: 0; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0; min-height: 0; border: 0; padding: 0; margin: 0} .MathJax_SVG * {transition: none; -webkit-transition: none; -moz-transition: none; -ms-transition: none; -o-transition: none} .mjx-svg-href {fill: blue; stroke: blue} .MathJax_SVG_LineBox {display: table!important} .MathJax_SVG_LineBox span {display: table-cell!important; width: 10000em!important; min-width: 0; max-width: none; padding: 0; border: 0; margin: 0}

You will be given an array of integers and a target value.  Determine the number of pairs of array elements that have a difference equal to a target value.

For example, given an array of [1, 2, 3, 4] and a target value of 1, we have three values meeting the condition: , , and .

Function Description

Complete the pairs function below.  It must return an integer representing the number of element pairs having the required difference.

pairs has the following parameter(s):

  • k: an integer, the target difference
  • arr: an array of integers

Input Format.MathJax_SVG_Display {text-align: center; margin: 1em 0em; position: relative; display: block!important; text-indent: 0; max-width: none; max-height: none; min-width: 0; min-height: 0; width: 100%} .MathJax_SVG .MJX-monospace {font-family: monospace} .MathJax_SVG .MJX-sans-serif {font-family: sans-serif} .MathJax_SVG {display: inline; font-style: normal; font-weight: normal; line-height: normal; font-size: 100%; font-size-adjust: none; text-indent: 0; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0; min-height: 0; border: 0; padding: 0; margin: 0} .MathJax_SVG * {transition: none; -webkit-transition: none; -moz-transition: none; -ms-transition: none; -o-transition: none} .mjx-svg-href {fill: blue; stroke: blue} .MathJax_SVG_LineBox {display: table!important} .MathJax_SVG_LineBox span {display: table-cell!important; width: 10000em!important; min-width: 0; max-width: none; padding: 0; border: 0; margin: 0}

The first line contains two space-separated integers  and , the size of  and the target value.
The second line contains  space-separated integers of the array .

Constraints.MathJax_SVG_Display {text-align: center; margin: 1em 0em; position: relative; display: block!important; text-indent: 0; max-width: none; max-height: none; min-width: 0; min-height: 0; width: 100%} .MathJax_SVG .MJX-monospace {font-family: monospace} .MathJax_SVG .MJX-sans-serif {font-family: sans-serif} .MathJax_SVG {display: inline; font-style: normal; font-weight: normal; line-height: normal; font-size: 100%; font-size-adjust: none; text-indent: 0; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0; min-height: 0; border: 0; padding: 0; margin: 0} .MathJax_SVG * {transition: none; -webkit-transition: none; -moz-transition: none; -ms-transition: none; -o-transition: none} .mjx-svg-href {fill: blue; stroke: blue} .MathJax_SVG_LineBox {display: table!important} .MathJax_SVG_LineBox span {display: table-cell!important; width: 10000em!important; min-width: 0; max-width: none; padding: 0; border: 0; margin: 0}

  • each integer  will be unique

Output Format.MathJax_SVG_Display {text-align: center; margin: 1em 0em; position: relative; display: block!important; text-indent: 0; max-width: none; max-height: none; min-width: 0; min-height: 0; width: 100%} .MathJax_SVG .MJX-monospace {font-family: monospace} .MathJax_SVG .MJX-sans-serif {font-family: sans-serif} .MathJax_SVG {display: inline; font-style: normal; font-weight: normal; line-height: normal; font-size: 100%; font-size-adjust: none; text-indent: 0; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0; min-height: 0; border: 0; padding: 0; margin: 0} .MathJax_SVG * {transition: none; -webkit-transition: none; -moz-transition: none; -ms-transition: none; -o-transition: none} .mjx-svg-href {fill: blue; stroke: blue} .MathJax_SVG_LineBox {display: table!important} .MathJax_SVG_LineBox span {display: table-cell!important; width: 10000em!important; min-width: 0; max-width: none; padding: 0; border: 0; margin: 0}

An integer representing the number of pairs of integers whose difference is .

Sample Input.MathJax_SVG_Display {text-align: center; margin: 1em 0em; position: relative; display: block!important; text-indent: 0; max-width: none; max-height: none; min-width: 0; min-height: 0; width: 100%} .MathJax_SVG .MJX-monospace {font-family: monospace} .MathJax_SVG .MJX-sans-serif {font-family: sans-serif} .MathJax_SVG {display: inline; font-style: normal; font-weight: normal; line-height: normal; font-size: 100%; font-size-adjust: none; text-indent: 0; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0; min-height: 0; border: 0; padding: 0; margin: 0} .MathJax_SVG * {transition: none; -webkit-transition: none; -moz-transition: none; -ms-transition: none; -o-transition: none} .mjx-svg-href {fill: blue; stroke: blue}

5 2  
1 5 3 4 2  

Sample Output.MathJax_SVG_Display {text-align: center; margin: 1em 0em; position: relative; display: block!important; text-indent: 0; max-width: none; max-height: none; min-width: 0; min-height: 0; width: 100%} .MathJax_SVG .MJX-monospace {font-family: monospace} .MathJax_SVG .MJX-sans-serif {font-family: sans-serif} .MathJax_SVG {display: inline; font-style: normal; font-weight: normal; line-height: normal; font-size: 100%; font-size-adjust: none; text-indent: 0; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0; min-height: 0; border: 0; padding: 0; margin: 0} .MathJax_SVG * {transition: none; -webkit-transition: none; -moz-transition: none; -ms-transition: none; -o-transition: none} .mjx-svg-href {fill: blue; stroke: blue}

3

Explanation.MathJax_SVG_Display {text-align: center; margin: 1em 0em; position: relative; display: block!important; text-indent: 0; max-width: none; max-height: none; min-width: 0; min-height: 0; width: 100%} .MathJax_SVG .MJX-monospace {font-family: monospace} .MathJax_SVG .MJX-sans-serif {font-family: sans-serif} .MathJax_SVG {display: inline; font-style: normal; font-weight: normal; line-height: normal; font-size: 100%; font-size-adjust: none; text-indent: 0; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0; min-height: 0; border: 0; padding: 0; margin: 0} .MathJax_SVG * {transition: none; -webkit-transition: none; -moz-transition: none; -ms-transition: none; -o-transition: none} .mjx-svg-href {fill: blue; stroke: blue} .MathJax_SVG_LineBox {display: table!important} .MathJax_SVG_LineBox span {display: table-cell!important; width: 10000em!important; min-width: 0; max-width: none; padding: 0; border: 0; margin: 0}

There are 3 pairs of integers in the set with a difference of 2: [5,3], [4,2] and [3,1] .

Solution in java8

Approach 1.

import java.io.*;
import java.util.*;

public class Solution {

    public static void main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        Scanner in = new Scanner(System.in);
    	int n = in.nextInt();
    	int k = in.nextInt();
    	int[] c = new int[n];
    	for (int i = 0; i < n; i++) {
    		c[i] = in.nextInt();
    	}
    	Arrays.sort(c);
    	int i = c.length - 1;
    	int j = c.length - 1;
    	int count = 0;
    	while (i > 0) {
    		while(c[i] - c[j] < k && j > 0) j--;
    		if (c[i] - c[j] == k) count++;
    		i--;
    	}
    	System.out.println(count);
    	in.close();
    }
}

Approach 2.

import java.io.*;
import java.util.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int k = in.nextInt();
        
        int pairCount = 0;
        Set<Integer> seen = new HashSet<>();
        
        for (int i = 0; i < n; i++) {
            int x = in.nextInt();
            
            if (Integer.MAX_VALUE - k >= x && seen.contains(x + k)) {
                pairCount++;
            }
            if (Integer.MIN_VALUE + k <= x && seen.contains(x - k)) {
                pairCount++;
            }
            
            seen.add(x);
        }
        
        System.out.println(pairCount);
    }
}

Approach 3.

import java.io.*;
import java.util.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int k = in.nextInt();

        int[] numbers = new int[n];
        for(int i=0; i<n; i++) {
            numbers[i] = in.nextInt();
        }

        Arrays.sort(numbers);

        int count = 0;
        for(int i=0; i<n; i++) {
            for(int j=i; j<n; j++) {

                if(numbers[j] - numbers[i] > k) {
                    break;
                }

                if(Math.abs(numbers[i] - numbers[j]) == k) {
                    count++;
                }
            }
        }

        System.out.println(count);

    }
}

Solution in python3

Approach 1.

#!/usr/bin/py
# Head ends here
def pairs(a,k):
    # a is the list of numbers and k is the difference value
    return len(set(a) & set(x + k for x in a))
# Tail starts here

if __name__ == '__main__':
    a = input().strip()
    a = list(map(int, a.split(' ')))
    _a_size=a[0]
    _k=a[1]
    b = input().strip()
    b = list(map(int, b.split(' ')))
    print(pairs(b,_k))

Approach 2.

#!/usr/bin/py
# Head ends here
def pairs(a,k):
    # a is the list of numbers and k is the difference value
    answer = len(set(a) & set(x+k for x in a))
    return answer
# Tail starts here
if __name__ == '__main__':
    a = input().strip()
    a = list(map(int, a.split(' ')))
    _a_size=a[0]
    _k=a[1]
    b = input().strip()
    b = list(map(int, b.split(' ')))
    print(pairs(b,_k))

Approach 3.

#!/usr/bin/py
# Head ends here
def pairs(a, k):
    d = {}
    answer = 0
    for i in a:
        d[i] = i
    for j in a:
        g = j+k
        if g in d:
            answer +=1
    return answer# Tail starts here
if __name__ == '__main__':
    a = input().strip()
    a = list(map(int, a.split(' ')))
    _a_size=a[0]
    _k=a[1]
    b = input().strip()
    b = list(map(int, b.split(' ')))
    print(pairs(b,_k))

Solution in cpp

Approach 1.

#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    int N,k,i,c=0;
	cin>>N>>k;
	vector<int> v(N);
	for (i = 0; i < N; i++)
	{
		cin>>v[i];
	}
	sort(v.begin(),v.end());
	i=0;
	for(int j = 1; j < N; j++)
	{
		if(v[j]-v[i]==k)
		{
			c++;
			i++;
		}
		else if(v[j]-v[i]>k)
		{
			i++;
			j--;
		}
	}

	cout<<c;
	return 0;
}

Approach 2.

#include <iostream>
#include <algorithm>
using namespace std;

int bsrch(int *a, int l, int h, int val)
{
	if(h<l)
		return -1;
	int m = (l+h)/2;
	if(a[m]==val)
		return m;
	if(a[m]>val)
		bsrch(a,l,m-1,val);
	else bsrch(a,m+1,h,val);
}

int main()
{
	int n,k;
	cin>>n>>k;
	int arr[n];
	for(int i=0;i<n;i++)
		cin>>arr[i];
	sort(arr, arr+n);

	int c=0,loc,t;
	for(int i=0;i<n;i++){
		loc = bsrch(arr,i,n-1,arr[i]+k);
		if(loc!=-1){
			c++; loc++;
			while(loc<n && arr[loc]==arr[i]+k){
				c++; loc++;
			}
		}
	}
	cout<<c<<endl;
	return 0;
}

Approach 3.

#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

int n, k, a[100000];
int ans = 0;
int head = 0;

void input() {
	cin >> n >> k;
	for(int i = 0; i < n; i++)
		cin >> a[i];
}

int findPairs(int x) {
	int p = a[x];
	while(true) {
		if(head >= n)
			return 0;
		if(a[head]-p == k) {
			head++;
			ans++;
			continue;
		}
		if(a[head]-p > k) {
			return 0;
		}
		if(a[head]-p < k) {
			head++;
			continue;
		}
	}
	return 0;
}

void solve() {
	sort(a,a+n);
	for(int i = 0; i < n; i++) {
		findPairs(i);
	}
	cout << ans << endl;
}

int main() {
	input();
	solve();
    return 0;
}


Enjoying these posts? Subscribe for more


Adblocker detected! Please consider reading this notice.

We've detected that you are using AdBlock Plus or some other adblocking software which is preventing the page from fully loading.

That's okay. But without advertising-income, we can't keep making this site awesome.

We don't have any banner, Flash, animation, obnoxious sound, or popup ad. We do not implement these annoying types of ads!

We need money to operate the site, and almost all of it comes from our online advertising.

Please add thepoorcoder.com to your ad blocking whitelist or disable your adblocking software.

×