Array Index & Element Equality | Pramp.Interview

[esthicodes]

Array Index & Element Equality

Given a sorted array arr of distinct integers, write a function indexEqualsValueSearch that returns the lowest index i for which arr[i] == i. Return -1 if there is no such index. Analyze the time and space complexities of your solution and explain its correctness.

Examples:

input: arr = [-8,0,2,5]
output: 2 # since arr[2] == 2

input: arr = [-1,0,3,6]
output: -1 # since no index in arr satisfies arr[i] == i.
Constraints:

[time limit] 5000ms

[input] array.integer arr

1 ≤ arr.length ≤ 100
[output] integer

[esthicodes]

def index_equals_value_search(arr):
  for i,d in enumerate(arr):
    if d==i:
      return i
  return -1

[esthicodes]

def index_equals_value_search(arr): # go through every index and number
  for i,d in enumerate(arr): #use enumerate when you want the index of a number 
    if d==i: # if the index equals the number. 
      return i # return index or the same 
  return -1 #if not, return negative one.