TapeEquilibrium

gistfile1.txt

Initial solution, test passing, 0% scores:

(1..a.size-2).each {|i| p (a.slice(i,a.size).inject(:+) - a.slice(0, i).inject(:+)) }.min

I found this on internet, 100% scores, very long:

    puts "tape_equilibrium: "
    return 0 if a.empty?
    # Example data: N=5, P(1-4), A[3,1,2,4,3]
    # P1:
    # [3] - [1,2,4,3]
    # [3,1] - [2,4,3]
    # [3,1,2] - [4,3]
    # [3,1,2,4] - [3]
    sum = a.inject(:+)
    left = a[0]
    right = sum - left
    min_diff = (right - left).abs
    for i in 1..(a.size-2) # -2 because the last iteration is the same as the first.
      left+= a[i]
      right-= a[i]
      diff = (right - left).abs
      min_diff = [min_diff, diff].min
    end
    min_diff
    
Last solution, 100%:

def solution(a)
    return if a.empty?
    tail = a.inject(:+) - a[0]
    head = a[0]
    min_dif = (head - tail).abs
    (1..a.size-2).each do |i|
        head += a[i];
        tail -= a[i];
        min_dif = (head-tail).abs if (head-tail).abs < min_dif
    end
    
    min_dif
end