Search sorted, pivoted array

x3.coffee

c = console.log.bind console
color = require 'bash-color'
_ = require 'lodash'
fp = require 'lodash/fp'


# this one gives the array above the pivot, inclusive of the pivot.
upper_rayy_incl = (rayy, pivot) ->
    [].concat rayy.slice(pivot)


# this one gives the array above the pivot, non-inclusive
upper_rayy = (rayy, pivot) ->
    [].concat rayy.slice(pivot + 1)


# this one gives the array below the pivot, non-inclusive
lower_rayy = (rayy, pivot) ->
    [].concat rayy.slice(0, pivot)


find_pivot = (rayy) ->
    pivot = -1
    for item, idx in rayy
        if item.val > rayy[idx + 1].val
            pivot = idx + 1
            break
    return pivot


binary_search = (rayy, target) ->
    midpoint_idx = Math.floor(rayy.length / 2)
    val_at_midpoint = rayy[midpoint_idx]
    unless val_at_midpoint is undefined
        if val_at_midpoint.val > target
            arguments.callee(lower_rayy(rayy, midpoint_idx), target)
        else if val_at_midpoint.val < target
            arguments.callee(upper_rayy(rayy, midpoint_idx), target)
        else if val_at_midpoint.val is target
            return val_at_midpoint.idx


exports.default = f2 = (rayy, target) ->
    pivot = find_pivot rayy
    if pivot is target
        return pivot
    else
        up_rayy = upper_rayy_incl(rayy, pivot)
        if target <= up_rayy[up_rayy.length - 1].val
            return binary_search up_rayy, target
        else
            c 'nought'
            low_rayy = lower_rayy(rayy, pivot)
            # c low_rayy
            return binary_search(low_rayy, target)


rayy = [59, 68, 77, 83, 123, 144,  8, 13, 38, 42]


rayy_x = _.map rayy, (val, idx) ->
    { val, idx }





for target, idx in rayy



    answer = f2 rayy_x, target

    c (color.cyan 'final', on),(color.white answer, on)

    # TEST
    if rayy[answer] isnt target
        c color.red "ERROR...", on
    else
        c color.green "GOOD ANSWER...", on