# Python: Sum of all items of a given array of integers where each integer is multiplied by its index

## Python Basic - 1: Exercise-100 with Solution

Write a Python program to compute the sum of all items in a given array of integers where each integer is multiplied by its index. Return 0 if there is no number.

**Sample Solution**:

**Python Code:**

```
# Define a function named sum_index_multiplier that takes a list of numbers (nums) as an argument.
def sum_index_multiplier(nums):
# Use a generator expression within the sum function to calculate the sum of each element multiplied by its index.
# The expression j*i for i, j in enumerate(nums) iterates over the elements and their indices.
return sum(j * i for i, j in enumerate(nums))
# Test the function with different lists of numbers and print the results.
# Test case 1
print(sum_index_multiplier([1,2,3,4]))
# Test case 2
print(sum_index_multiplier([-1,-2,-3,-4]))
# Test case 3
print(sum_index_multiplier([]))
```

Sample Output:

20 -20 0

**Explanation:**

Here is a breakdown of the above Python code:

- Function definition:
- The code defines a function named "sum_index_multiplier()" that takes a list of numbers (nums) as an argument.
- Generator Expression and Enumerate:
- The function uses a generator expression within the "sum()" function to calculate the sum of each element multiplied by its index. The expression j * i for i, j in enumerate(nums) iterates over the elements and their indices.
- Return Statement:
- The function returns the result of the sum operation.

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