# Find pairs of Positive and Negative values present in given array

Given an array of distinct integers, print all the pairs having both positive and negative values of a number that exists in the array. The pairs can be printed in any order.

Examples:

Input:  arr[] = {1, -3, 2, 3, 6, -1}
Output: -1 1 -3 3

Input:  arr[] = {4, 8, 9, -4, 1, -1, -8, -9}
Output: -4 4 -8 8 -9 9 -1 1

Recommended Practice

Naive Approach: To solve the problem follow the below idea:

The idea is to use two nested loops. For each element arr[i], find negative of arr[i] from index i + 1 to n – 1 and store it in another array

Below is the implementation of this approach:

## C++

 `// Simple CPP program to find pairs of positive``// and negative values present in an array.``#include ``using` `namespace` `std;` `// Print pair with negative and positive value``void` `printPairs(``int` `arr[], ``int` `n)``{``    ``vector<``int``> v;` `    ``// For each element of array.``    ``for` `(``int` `i = 0; i < n; i++)` `        ``// Try to find the negative value of``        ``// arr[i] from i + 1 to n``        ``for` `(``int` `j = i + 1; j < n; j++)` `            ``// If absolute values are equal print pair.``            ``if` `(``abs``(arr[i]) == ``abs``(arr[j]))``                ``v.push_back(``abs``(arr[i]));` `    ``// If size of vector is 0, therefore there is no``    ``// element with positive negative value, print "0"``    ``if` `(v.size() == 0)``        ``return``;` `    ``// Print the pair with negative positive value.``    ``for` `(``int` `i = 0; i < v.size(); i++)``        ``cout << -v[i] << ``" "` `<< v[i] << ``" "``;``}` `// Driver code``int` `main()``{``    ``int` `arr[] = { 4, 8, 9, -4, 1, -1, -8, -9 };``    ``int` `n = ``sizeof``(arr) / ``sizeof``(arr[0]);` `    ``// Function call``    ``printPairs(arr, n);``    ``return` `0;``}`

## Java

 `// Java program to find pairs of positive``// and negative values present in an array.``import` `java.lang.*;``import` `java.util.*;` `class` `GFG {` `    ``// Print pair with negative and positive value``    ``public` `static` `void` `printPairs(``int` `arr[], ``int` `n)``    ``{``        ``Vector v = ``new` `Vector();``        ``// For each element of array.``        ``for` `(``int` `i = ``0``; i < n; i++)` `            ``// Try to find the negative value of``            ``// arr[i] from i + 1 to n``            ``for` `(``int` `j = i + ``1``; j < n; j++)` `                ``// If absolute values are equal``                ``// print pair.``                ``if` `(Math.abs(arr[i]) == Math.abs(arr[j]))``                    ``v.add(Math.abs(arr[i]));` `        ``// If size of vector is 0, therefore there``        ``// is no element with positive negative``        ``// value, print "0"``        ``if` `(v.size() == ``0``)``            ``return``;` `        ``// Print the pair with negative positive``        ``// value.``        ``for` `(``int` `i = ``0``; i < v.size(); i++)``            ``System.out.print(-v.get(i) + ``" "` `+ v.get(i)``                             ``+ ``" "``);``    ``}` `    ``// Driver code``    ``public` `static` `void` `main(String[] args)``    ``{``        ``int` `arr[] = { ``4``, ``8``, ``9``, -``4``, ``1``, -``1``, -``8``, -``9` `};``        ``int` `n = arr.length;` `        ``// Function call``        ``printPairs(arr, n);``    ``}``}` `// This code is contributed by Prasad Kshirsagar.`

## Python 3

 `# Simple Python 3 program to find``# pairs of positive and negative``# values present in an array.` `# Print pair with negative and``# positive value`  `def` `printPairs(arr, n):``    ``v ``=` `[]` `    ``# For each element of array.``    ``for` `i ``in` `range``(n):` `        ``# Try to find the negative value``        ``# of arr[i] from i + 1 to n``        ``for` `j ``in` `range``(i ``+` `1``, n):` `            ``# If absolute values are``            ``# equal print pair.``            ``if` `(``abs``(arr[i]) ``=``=` `abs``(arr[j])):``                ``v.append(``abs``(arr[i]))` `    ``# If size of vector is 0, therefore``    ``# there is no element with positive``    ``# negative value, print "0"``    ``if` `(``len``(v) ``=``=` `0``):``        ``return` `    ``# Print the pair with negative``    ``# positive value.``    ``for` `i ``in` `range``(``len``(v)):``        ``print``(``-``v[i], "``", v[i], end="` `")`  `# Driver Code``if` `__name__ ``=``=` `"__main__"``:``    ``arr ``=` `[``4``, ``8``, ``9``, ``-``4``, ``1``, ``-``1``, ``-``8``, ``-``9``]``    ``n ``=` `len``(arr)` `    ``# Function call``    ``printPairs(arr, n)` `# This code is contributed``# by ChitraNayal`

## C#

 `// C# program to find pairs of positive``// and negative values present in an array.``using` `System;``using` `System.Collections.Generic;` `class` `GFG {` `    ``// Print pair with negative and positive value``    ``public` `static` `void` `printPairs(``int``[] arr, ``int` `n)``    ``{``        ``List<``int``> v = ``new` `List<``int``>();` `        ``// For each element of array.``        ``for` `(``int` `i = 0; i < n; i++)` `            ``// Try to find the negative value of``            ``// arr[i] from i + 1 to n``            ``for` `(``int` `j = i + 1; j < n; j++)` `                ``// If absolute values are equal``                ``// print pair.``                ``if` `(Math.Abs(arr[i]) == Math.Abs(arr[j]))``                    ``v.Add(Math.Abs(arr[i]));` `        ``// If size of vector is 0, therefore there``        ``// is no element with positive negative``        ``// value, print "0"``        ``if` `(v.Count == 0)``            ``return``;` `        ``// Print the pair with negative positive``        ``// value.``        ``for` `(``int` `i = 0; i < v.Count; i++)``            ``Console.Write(-v[i] + ``" "` `+ v[i] + ``" "``);``    ``}` `    ``// Driver code``    ``public` `static` `void` `Main(String[] args)``    ``{``        ``int``[] arr = { 4, 8, 9, -4, 1, -1, -8, -9 };``        ``int` `n = arr.Length;` `        ``// Function call``        ``printPairs(arr, n);``    ``}``}` `// This code has been contributed by 29AjayKumar`

## Javascript

 ``

Output
`-4 4 -8 8 -9 9 -1 1 `

Time Complexity: O(N2)
Auxiliary Space: O(N)

## Find pairs of Positive and Negative values present in given array using hashing:

To solve the problem follow the below idea:

The idea is to use hashing to store count of absolute value of every element present in the array. If the count of any element is equal to 2, then it means that a pair has been found

Follow the given steps to solve the problem:

• Traverse the given array, and increase the count at the absolute value of the hash table.
• If the count becomes 2, store its absolute value in another vector.
• If the size of the vector is 0, print “0”,
• else for each term in the vector print first its negative value and the positive value

Below is the implementation of this approach:

## C++

 `// CPP program to find pairs of``// positive and negative values present in``// an array.``#include ``using` `namespace` `std;` `// Print pair with negative and positive value``void` `printPairs(``int` `arr[], ``int` `n)``{``    ``vector<``int``> v;``    ``unordered_map<``int``, ``bool``> cnt;` `    ``// For each element of array.``    ``for` `(``int` `i = 0; i < n; i++) {` `        ``// If element has not encounter early,``        ``// mark it on cnt array.``        ``if` `(cnt[``abs``(arr[i])] == 0)``            ``cnt[``abs``(arr[i])] = 1;` `        ``// If seen before, push it in vector (``        ``// given that elements are distinct)``        ``else` `{``            ``v.push_back(``abs``(arr[i]));``            ``cnt[``abs``(arr[i])] = 0;``        ``}``    ``}` `    ``if` `(v.size() == 0)``        ``return``;` `    ``for` `(``int` `i = 0; i < v.size(); i++)``        ``cout << ``"-"` `<< v[i] << ``" "` `<< v[i] << ``" "``;``}` `// Driver code``int` `main()``{``    ``int` `arr[] = { 4, 8, 9, -4, 1, -1, -8, -9 };``    ``int` `n = ``sizeof``(arr) / ``sizeof``(arr[0]);` `    ``// Function call``    ``printPairs(arr, n);` `    ``return` `0;``}`

## Java

 `// Java program to find pairs of``// positive and negative values present in``// an array.``import` `java.util.*;``class` `GFG {` `    ``// Print pair with negative``    ``// and positive value``    ``static` `void` `printPairs(``int` `arr[], ``int` `n)``    ``{``        ``ArrayList v = ``new` `ArrayList();``        ``HashMap cnt``            ``= ``new` `HashMap();` `        ``// For each element of array.``        ``for` `(``int` `i = ``0``; i < n; i++) {` `            ``// If element has encounter early,``            ``// then increment its count``            ``if` `(cnt.containsKey(Math.abs(arr[i])))``                ``cnt.put(Math.abs(arr[i]),``                        ``cnt.get(Math.abs(arr[i])) + ``1``);` `            ``// If element has not seen before,``            ``// then initialize its count to 1``            ``else` `{``                ``cnt.put(Math.abs(arr[i]), ``1``);``            ``}``            ``if` `(cnt.get(Math.abs(arr[i])) == ``2``) {``                ``v.add(Math.abs(arr[i]));``            ``}``        ``}``        ``if` `(v.size() == ``0``)``            ``return``;` `        ``for` `(``int` `i = ``0``; i < v.size(); i++)``            ``System.out.print(``"-"` `+ v.get(i) + ``" "` `+ v.get(i)``                             ``+ ``" "``);``    ``}` `    ``// Driver Code``    ``public` `static` `void` `main(String[] args)``    ``{``        ``int` `arr[] = { ``4``, ``8``, ``9``, -``4``, ``1``, -``1``, -``8``, -``9` `};``        ``int` `n = arr.length;` `        ``// Function call``        ``printPairs(arr, n);``    ``}``}``// This code is contributed by Prerna Saini`

## Python3

 `# Python3 program to find pairs of``# positive and negative values present in``# an array.``# Print pair with negative and``# positive value`  `def` `printPairs(arr, n):` `    ``s ``=` `set``()``    ``ret ``=` `[]` `    ``# For each element of array.``    ``for` `i ``in` `arr:``        ``if` `abs``(i) ``in` `s:``            ``ret.append(``abs``(i))``        ``else``:``            ``s.add(``abs``(i))` `    ``ret.sort()` `    ``for` `i ``in` `range``(``0``, ``len``(ret)):``        ``print``(``-``ret[i], "``", ret[i], end="` `")`  `# Driver Code``if` `__name__ ``=``=` `"__main__"``:``    ``arr ``=` `[``4``, ``8``, ``9``, ``-``4``, ``1``, ``-``1``, ``-``8``, ``-``9``]``    ``n ``=` `len``(arr)` `    ``# Function call``    ``printPairs(arr, n)``# This code is contributed by RohitOberoi`

## C#

 `// C# program to find pairs of``// positive and negative values present in``// an array.``using` `System;``using` `System.Collections.Generic;``class` `GFG {` `    ``// Print pair with negative and positive value``    ``static` `void` `printPairs(``int``[] arr, ``int` `n)``    ``{``        ``List<``int``> v = ``new` `List<``int``>();``        ``Dictionary<``int``, ``bool``> cnt``            ``= ``new` `Dictionary<``int``, ``bool``>();` `        ``// For each element of array.``        ``for` `(``int` `i = 0; i < n; i++) {` `            ``// If element has not encounter early,``            ``// mark it on cnt array.``            ``int` `absVal = Math.Abs(arr[i]);``            ``if` `(!cnt.ContainsKey(absVal)) {``                ``cnt[absVal] = ``true``;``            ``}``            ``else` `if` `(cnt[absVal] == ``false``) {``                ``cnt[absVal] = ``true``;``            ``}``            ``else` `{``                ``v.Add(Math.Abs(arr[i]));``                ``cnt[absVal] = ``false``;``            ``}``        ``}` `        ``if` `(v.Count == 0)``            ``return``;` `        ``v.Sort();``        ``for` `(``int` `i = 0; i < v.Count; i++)``            ``Console.Write(-v[i] + ``" "` `+ v[i] + ``" "``);``    ``}` `    ``// Driver code``    ``static` `void` `Main()``    ``{``        ``int``[] arr = { 4, 8, 9, -4, 1, -1, -8, -9 };``        ``int` `n = arr.Length;` `        ``// Function call``        ``printPairs(arr, n);``    ``}``}``// This code is contributed by divyeshrabadiya07`

## Javascript

 ``

Output
`-4 4 -1 1 -8 8 -9 9 `

Time Complexity: O(N)
Auxiliary Space: O(N)

## Find pairs of Positive and Negative values present in given array using set:

To solve the problem follow the below idea:

The idea is to use a set. Find the negative of the number in the set. If it exits then print both the numbers and if it does not exist then add it to the set

Below is the implementation of this approach:

## C++

 `// CPP program to find pairs of``// positive and negative values present in``// an array.``#include ``using` `namespace` `std;` `// Print pair with negative and positive value``void` `printPairs(``int` `arr[], ``int` `n)``{``    ``unordered_set<``int``> hs;``    ``vector<``int``> ans;``    ``for` `(``int` `i = 0; i < n; i++) {``        ``if` `(hs.find((arr[i]) * -1) != hs.end()) {``            ``if` `(arr[i] < 0) {``                ``cout << arr[i] << ``" "``;``                ``cout << (arr[i] * -1) << ``" "``;``            ``}``            ``else` `{``                ``cout << (arr[i] * -1) << ``" "``;``                ``cout << arr[i] << ``" "``;``            ``}``        ``}``        ``hs.insert(arr[i]);``    ``}` `    ``return``;``}` `// Driver code``int` `main()``{``    ``int` `arr[] = { 4, 8, 9, -4, 1, -1, -8, -9 };``    ``int` `n = ``sizeof``(arr) / ``sizeof``(arr[0]);` `    ``// Function call``    ``printPairs(arr, n);``    ``return` `0;``}`

## Java

 `// Java program to find pairs of``// positive and negative values present in``// an array.``import` `java.util.*;` `public` `class` `GFG {` `    ``// Print pair with negative and positive value``    ``public` `static` `void` `printPairs(``int``[] arr, ``int` `n)``    ``{``        ``HashSet hs = ``new` `HashSet();``        ``ArrayList ans = ``new` `ArrayList();``        ``for` `(``int` `i = ``0``; i < n; i++) {``            ``if` `(hs.contains((arr[i]) * -``1``)) {``                ``if` `(arr[i] < ``0``) {``                    ``System.out.print(arr[i]);``                    ``System.out.print(``" "``);``                    ``System.out.print((arr[i] * -``1``));``                    ``System.out.print(``" "``);``                ``}``                ``else` `{``                    ``System.out.print((arr[i] * -``1``));``                    ``System.out.print(``" "``);``                    ``System.out.print(arr[i]);``                    ``System.out.print(``" "``);``                ``}``            ``}` `            ``hs.add(arr[i]);``        ``}` `        ``return``;``    ``}` `    ``// Driver code``    ``public` `static` `void` `main(String[] args)``    ``{``        ``int``[] arr = { ``4``, ``8``, ``9``, -``4``, ``1``, -``1``, -``8``, -``9` `};``        ``int` `n = arr.length;` `        ``// Function call``        ``printPairs(arr, n);``    ``}``}` `// This code is contributed by Aarti_Rathi`

## Python3

 `# Python3 program to find pairs of``# positive and negative values present in``# an array`  `def` `printPairs(arr, n):` `    ``hs ``=` `set``()``    ``ans ``=` `[]``    ``for` `i ``in` `range``(n):``        ``if` `(arr[i] ``*` `-``1``) ``in` `hs:` `            ``if` `(arr[i] < ``0``):``                ``print``(arr[i], end``=``" "``)``                ``print``((arr[i] ``*` `-``1``), end``=``" "``)` `            ``else``:``                ``print``((arr[i] ``*` `-``1``), end``=``" "``)``                ``print``(arr[i], end``=``" "``)` `        ``hs.add(arr[i])` `    ``return`  `# Driver code``arr ``=` `[``4``, ``8``, ``9``, ``-``4``, ``1``, ``-``1``, ``-``8``, ``-``9``]``n ``=` `len``(arr)` `# Function call``printPairs(arr, n)` `# This code is contributed by shinjanpatra.`

## C#

 `// C# program to find pairs of positive and``// negative values present in an array.``using` `System;``using` `System.Collections;``using` `System.Collections.Generic;` `public` `class` `GFG {` `    ``// Print pair with negative and positive value``    ``public` `static` `void` `printPairs(``int``[] arr, ``int` `n)``    ``{``        ``HashSet<``int``> hs = ``new` `HashSet<``int``>();``        ``for` `(``int` `i = 0; i < n; i++) {``            ``if` `(hs.Contains((arr[i]) * -1)) {``                ``if` `(arr[i] < 0) {``                    ``Console.Write(arr[i]);``                    ``Console.Write(``" "``);``                    ``Console.Write((arr[i] * -1));``                    ``Console.Write(``" "``);``                ``}``                ``else` `{``                    ``Console.Write((arr[i] * -1));``                    ``Console.Write(``" "``);``                    ``Console.Write(arr[i]);``                    ``Console.Write(``" "``);``                ``}``            ``}``            ``hs.Add(arr[i]);``        ``}` `        ``return``;``    ``}` `    ``// Driver code``    ``static` `public` `void` `Main()``    ``{``        ``int``[] arr = { 4, 8, 9, -4, 1, -1, -8, -9 };``        ``int` `n = arr.Length;` `        ``// Function call``        ``printPairs(arr, n);``    ``}``}` `// This code is contributed by lokeshmvs21.`

## Javascript

 ``

Output
`-4 4 -1 1 -8 8 -9 9 `

Time Complexity: O(N)
Auxiliary Space: O(N)

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