Palindromes

daily-coding-problem-46.rb

def all_palindromes(word)
    q = "@#"
    q += word.chars.join("#")
    q += "\#$"
    puts q
    pld = [0] * q.size()
    c,r = 0,0
    search = (1...q.size())
    search.each do |i|
        mirror = c - (i - c)
        if r > i
            pld[i] = [r - 1, pld[mirror]].min 
        end
        while q[i+1+pld[i]] == q[i-1-pld[i]]
            pld[i] += 1
        end 
        if i+pld[i] > r
            c = i 
            r = i + pld[i]
        end
    end 
    max_pld,ctr_idx = 0,0 
    search.each do |i|
        if pld[i] > max_pld 
            max_pld = pld[i]
            ctr_idx = i
        end  
    end 
    puts max_pld
    return word[(ctr_idx - 1 - max_pld)/2, max_pld]
end

word = "banana"
puts all_palindromes(word)