/php-array-mutation

Primary LanguagePHP

Array mutation - PHP

Given an integer n and an array a of length n, your task is to apply the following mutation to a:

  • Array a mutates into a new array b of length n.
  • For each i from 0 to n - 1, b[i] = a[i - 1] + a[i] + a[i + 1].
  • If some element in the sum a[i - 1] + a[i] + a[i + 1] does not exist, it should be set to 0. For example, b[0] should be equal to 0 + a[0] + a[1].

Example

For n = 5 and a = [4, 0, 1, -2, 3], the output should be solution(n, a) = [4, 5, -1, 2, 1].

  • b[0] = 0 + a[0] + a[1] = 0 + 4 + 0 = 4
  • b[1] = a[0] + a[1] + a[2] = 4 + 0 + 1 = 5
  • b[2] = a[1] + a[2] + a[3] = 0 + 1 + (-2) = -1
  • b[3] = a[2] + a[3] + a[4] = 1 + (-2) + 3 = 2
  • b[4] = a[3] + a[4] + 0 = (-2) + 3 + 0 = 1 So, the resulting array after the mutation will be [4, 5, -1, 2, 1].

Input/Output

  • [execution time limit] 4 seconds (php)
  • [input] integer n 
An integer representing the length of the given array.
Guaranteed constraints:
1 ≤ n ≤ 103.
  • [input] array.integer a 
An array of integers that needs to be mutated.
Guaranteed constraints:
a.length = n,
-103 ≤ a[i] ≤ 103.
  • [output] array.integer
 The resulting array after the mutation.