2Sum Problem

2Sum Problem

The 2sum is a famous problem asked in most interviews. We have to check whether a pair of numbers exists whose sum is equal to the target value. We are given an array of integers and the target value. We have to return true if the pair whose sum is equal to the target value exists else we have to return false....

Following are the approaches

Table of Content Brute Force Method Hashing Method Two Pointer Method...

Approach 1: Brute Force Method

The Two Sum issue may be solved brute-force style by using nested loops to iteratively verify every possible pair of integers in the array. However, for big datasets, this strategy is inefficient due to its O(n2) time complexity, where n is the array’s size....

Approach 2: Hashing Method

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Approach 3: Two Pointer Method

A more effective method stores the array’s items and their indexes in a hash table (or dictionary). This makes constant-time lookups possible. As the method loops across the array, it determines each element’s complement (goal sum minus the current element) and verifies that it is present in the hash table. If it is located, it provides the indices of the element that is now active as well as its complement; this has an O(n) time complexity....