Equi index attempts (w/fail details)

gistfile1.txt

FIRST ATTEMPT

Code: 23:58:40 UTC, rb, final, score:  17.00

def solution(a)
    a.length.times do |index|
        if index == 0 
            return index if a[1..-1].reduce(:+) == 0
        elsif a[0...index].reduce(:+) == a[index+1..-1].reduce(:+) 
            return index
        else
            return -1
        end
    end
end

Analysis summary
The following issues have been detected: wrong answers.

For example, for the input [] the solution returned a wrong answer (got 0, which is not valid array index).

Analysis
expand allExample tests
▶ example 
Test from the task description ✔OK
expand allCorrectness tests
▶ simple ✔OK
▶ extreme_large_numbers 
Sequence with extremely large numbers testing arithmetic overflow. ✔OK
▶ extreme_negative_numbers 
Sequence with extremely large numbers testing arithmetic overflow. ✘WRONG ANSWER 
got 1, which is not valid array index
▶ overflow_tests1 
arithmetic overflow tests ✔OK
▶ overflow_tests2 
arithmetic overflow tests ✘WRONG ANSWER 
got -1, but equilibrium point exists, for example on position 2 of A = [0, 2147483647, 2147483647, 2147483647]
▶ one_large 
one large number at the end of the sequence ✘WRONG ANSWER 
got -1, but equilibrium point exists, for example on position 4 of A = [2, -1, -2, 1, 500]
1. 0.098 s OK
2. 0.102 s WRONG ANSWER,  got -1, but equilibrium point exists, for example on position 4 of A = [2, -1, -2, 1, 500]
▶ sum_0 
sequence with sum=0 ✘WRONG ANSWER 
got -1, but equilibrium point exists, for example on position 3 of A = [1, 2, -3, 0]
1. 0.099 s OK
2. 0.099 s WRONG ANSWER,  got -1, but equilibrium point exists, for example on position 3 of A = [1, 2, -3, 0]
▶ single_empty 
single number or empty array ✘WRONG ANSWER 
got 1, which is not valid array index
▶ combinations_of_two 
multiple runs, all pairs of values: -1, 0 and 1 ✘WRONG ANSWER 
got -1, but equilibrium point exists, for example on position 1 of A = [0, -1]
1. 0.100 s OK
2. 0.101 s OK
3. 0.103 s OK
4. 0.100 s WRONG ANSWER,  got -1, but equilibrium point exists, for example on position 1 of A = [0, -1]
5. 0.102 s OK
6. 0.100 s WRONG ANSWER,  got -1, but equilibrium point exists, for example on position 1 of A = [0, 1]
7. 0.101 s OK
8. 0.101 s OK
9. 0.099 s OK
▶ combinations_of_three 
multiple runs, all triples of values -1, 0 and 1 ✘WRONG ANSWER 
got -1, but equilibrium point exists, for example on position 2 of A = [-1, 1, 0]
▶ small_pyramid ✘WRONG ANSWER 
got -1, but equilibrium point exists, for example on position 42
expand allCorrectness/performance tests
▶ extreme_max 
Maximal size test ✘WRONG ANSWER 
got -1, but equilibrium point exists, for example on position 26681
expand allPerformance tests
▶ large_long_sequence_of_ones ✘WRONG ANSWER 
got -1, but equilibrium point exists, for example on position 49998
1. 0.145 s WRONG ANSWER,  got -1, but equilibrium point exists, for example on position 49998
▶ large_long_sequence_of_minus_ones ✘WRONG ANSWER 
got -1, but equilibrium point exists, for example on position 50001
1. 0.147 s OK
2. 0.148 s WRONG ANSWER,  got -1, but equilibrium point exists, for example on position 50001
▶ medium_pyramid ✘WRONG ANSWER 
got -1, but equilibrium point exists, for example on position 62
▶ large_pyramid 
Large performance test, O(n^2) solutions should fail. ✘WRONG ANSWER 
got -1, but equilibrium point exists, for example on position 198
▶ huge_pyramid 
Large performance test, O(n^2) solutions should fail. ✘WRONG ANSWER 
got -1, but equilibrium point exists, for example on position 630

SECOND ATTEMPT

Code: 00:53:01 UTC, rb, final, score:  64.00

def solution(a)
    a.length.times do |index|
        if index == 0 
            return index if a[1..-1].reduce(:+) == 0
        elsif index == a.length-1
            return index if a[0...index].reduce(:+) == 0
        elsif a[0...index].reduce(:+) == a[index+1..-1].reduce(:+) 
            return index
        end
    end
    return -1
end

Analysis summary
The following issues have been detected: wrong answers, timeout errors.

For example, for the input [0] the solution returned a wrong answer (got -1, but equilibrium point exists, for example on position 0 of A = [0]).

Analysis
Detected time complexity:
O(N**2)
expand allExample tests
▶ example 
Test from the task description ✔OK
expand allCorrectness tests
▶ simple ✔OK
▶ extreme_large_numbers 
Sequence with extremely large numbers testing arithmetic overflow. ✔OK
▶ extreme_negative_numbers 
Sequence with extremely large numbers testing arithmetic overflow. ✘WRONG ANSWER 
got -1, but equilibrium point exists, for example on position 0 of A = [-2147483648]
1. 0.098 s WRONG ANSWER,  got -1, but equilibrium point exists, for example on position 0 of A = [-2147483648]
2. 0.102 s OK
3. 0.099 s OK
▶ overflow_tests1 
arithmetic overflow tests ✔OK
▶ overflow_tests2 
arithmetic overflow tests ✔OK
▶ one_large 
one large number at the end of the sequence ✔OK
▶ sum_0 
sequence with sum=0 ✔OK
▶ single_empty 
single number or empty array ✘WRONG ANSWER 
got -1, but equilibrium point exists, for example on position 0 of A = [0]
▶ combinations_of_two 
multiple runs, all pairs of values: -1, 0 and 1 ✔OK
▶ combinations_of_three 
multiple runs, all triples of values -1, 0 and 1 ✔OK
▶ small_pyramid ✔OK
expand allCorrectness/performance tests
▶ extreme_max 
Maximal size test ✘TIMEOUT ERROR 
running time: >6.00 sec., time limit: 0.60 sec.
expand allPerformance tests
▶ large_long_sequence_of_ones ✘TIMEOUT ERROR 
running time: >6.00 sec., time limit: 0.60 sec.
▶ large_long_sequence_of_minus_ones ✘TIMEOUT ERROR 
running time: >6.00 sec., time limit: 0.61 sec.
▶ medium_pyramid ✔OK
▶ large_pyramid 
Large performance test, O(n^2) solutions should fail. ✔OK
▶ huge_pyramid 
Large performance test, O(n^2) solutions should fail. ✘TIMEOUT ERROR 
running time: 3.49 sec., time limit: 0.58 sec.

THIRD ATTEMPT

Code: 02:56:28 UTC, rb, final, score:  100.00

def solution(a)
  left = 0
  right = a.reduce(:+)
  a.each_with_index do |value, index|
    if index == 0
      right -= value
      return index if a.length == 1 || right == 0
    elsif index == a.length-1
      left += a[index-1]
      return index if left == 0
    else
      left += a[index-1]
      right -= value
      return index if left == right
    end
  end
  return -1
end
Analysis summary
The solution obtained perfect score.

Analysis
Detected time complexity:
O(N)
expand allExample tests
▶ example 
Test from the task description ✔OK
expand allCorrectness tests
▶ simple ✔OK
▶ extreme_large_numbers 
Sequence with extremely large numbers testing arithmetic overflow. ✔OK
▶ extreme_negative_numbers 
Sequence with extremely large numbers testing arithmetic overflow. ✔OK
▶ overflow_tests1 
arithmetic overflow tests ✔OK
▶ overflow_tests2 
arithmetic overflow tests ✔OK
▶ one_large 
one large number at the end of the sequence ✔OK
▶ sum_0 
sequence with sum=0 ✔OK
▶ single_empty 
single number or empty array ✔OK
▶ combinations_of_two 
multiple runs, all pairs of values: -1, 0 and 1 ✔OK
▶ combinations_of_three 
multiple runs, all triples of values -1, 0 and 1 ✔OK
▶ small_pyramid ✔OK
expand allCorrectness/performance tests
▶ extreme_max 
Maximal size test ✔OK
expand allPerformance tests
▶ large_long_sequence_of_ones ✔OK
▶ large_long_sequence_of_minus_ones ✔OK
▶ medium_pyramid ✔OK
▶ large_pyramid 
Large performance test, O(n^2) solutions should fail. ✔OK
▶ huge_pyramid 
Large performance test, O(n^2) solutions should fail. ✔OK