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PairEqualSum.java
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PairEqualSum.java
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package Hashing;
import java.util.HashMap;
import java.util.Map;
/**
* @author kalpak
* Given an array of distinct integers, find if there are two pairs (a, b) and (c, d) such that a+b = c+d, and a, b, c and d are distinct elements.
* If there are multiple answers, then print any of them.
*
* Example:
*
* Input: {3, 4, 7, 1, 2, 9, 8}
* Output: (3, 8) and (4, 7)
* Explanation: 3+8 = 4+7
*
* Input: {3, 4, 7, 1, 12, 9};
* Output: (4, 12) and (7, 9)
* Explanation: 4+12 = 7+9
*
* Input: {65, 30, 7, 90, 1, 9, 8};
* Output: No pairs found
*/
public class PairEqualSum {
public static void findPairWithEqualSum(int[] arr) {
Map<Integer, Integer[]> map = new HashMap<>();
for (int i = 0; i < arr.length; i++) {
for (int j = 0; j < arr.length; j++) {
if (i != j) {
Integer sum = arr[i] + arr[j];
if(map.get(sum) != null) {
Integer[] a= map.get(sum);
if((arr[i]^arr[j]^a[0]^a[1]) != 0) { // check that the pair should not be the same
System.out.println(map.get(sum)[0]+" "+ map.get(sum)[1]);
System.out.println(arr[i]+" "+arr[j]);
return;
}
} else {
map.put(sum, new Integer[]{arr[i], arr[j]});
}
}
}
}
}
public static void main(String[] args) {
findPairWithEqualSum(new int[]{3, 4, 7, 1, 2, 9, 8});
}
}