Data Structure & Algorithms
DSA
Introduction to arrays
Good Pair

# Good Pair

## Problem Description

Given an array A and an integer B. A pair(i, j) in the array is a good pair if i != j and (A[i] + A[j] == B). Check if any good pair exist or not.

### Problem Constraints

``````1 <= A.size() <= 10^4
1 <= A[i] <= 10^9
1 <= B <= 10^9``````

### Input Format

``````First argument is an integer array A.
Second argument is an integer B.``````

### Output Format

``Return 1 if good pair exist otherwise return 0.``

### Example Input

``````Input 1:
A = [1,2,3,4]
B = 7

Input 2:
A = [1,2,4]
B = 4

Input 3:
A = [1,2,2]
B = 4``````

### Example Output

``````Output 1:
1

Output 2:
0

Output 3:
1``````

### Example Explanation

``````Explanation 1:
(i,j) = (3,4)

Explanation 2:
No pair has sum equal to 4.

Explanation 3:
(i,j) = (2,3)``````

### Output

Java
``````import java.util.HashSet;

public class GoodPair {
public int solve(int[] A, int B) {
HashSet<Integer> set = new HashSet<>();
for (int num : A) {
if (set.contains(B - num)) {
return 1;
}
}
return 0;
}
}``````
Python
``````def solve(A, B):
seen = set()
for num in A:
if B - num in seen:
return 1
``````function solve(A, B) {