This code defines a `MyClass` that searches for two distinct...

This code defines a MyClass that searches for two distinct indices in a list whose corresponding values sum to a target value. Let's break it down step by step:

Code Walkthrough

1. __init__ method:

   • The constructor __init__ initializes two attributes:
     • self.lookup: An empty dictionary intended to store previously visited vals values as keys and their indices as values.
     • self.vals: A list of numbers provided when creating a MyClass instance.

2. method function:

   • Accepts a target value.
   • Iterates through each value in the vals list.
   • For each value in vals, it:
     1. Computes the difference between the target and the current number num (target - num).
     2. Checks if this difference exists in the self.lookup dictionary:
        • If it exists, the method returns a tuple: (index of target - num, index of num).
     3. If the difference does not exist, it adds the current value num with its index i to the self.lookup dictionary for potential future matches.

3. Usage:

   • The code creates two instances of MyClass and performs specific operations:

     • First Instance:

       1. The a object is initialized with [10, 20, 10, 40].
       2. The method a.method(50) finds indices (1, 3) because vals[1] + vals[3] = 20 + 40 = 50. The first index (1) is stored in res1.
       3. The method a.method(30) finds indices (0, 1) because vals[0] + vals[1] = 10 + 20 = 30. The second index (1) is stored in res2.

     • Second Instance:

       1. The b object is initialized with [10, 20, 10, 40].
       2. The method b.method(30) called on b again finds indices (0, 1) for vals[0] + vals[1] = 10 + 20 = 30. The second index (1) is stored in res3.

Outputs:

• res1: This is the first index from the tuple returned by a.method(50), which is 1.
• res2: This is the second index from the tuple returned by a.method(30), which is 1.
• res3: This is the second index from the tuple returned by b.method(30), which is 1.

Key Observations:

• Instance-specific state: Each object of MyClass has its own independent lookup dictionary. This is why results of a and b don't interfere with one another.
• Purpose: The method function essentially solves a variation of the "two-sum problem", where it finds two indices such that their values add up to a given target.