import random

def above(i):
    """ Return index of heap slot above one """
    # Here's what it looks like:
    #         0
    #       1     2
    #     3  4   5  6
    # so above(3) = above(4) = 1
    #
    if i == 0:
        return 0
    else:
        return (i-1)/2

class Heap(object):
    """ minimum heap implementation """
    # TODO: add error checking so that max_size isn't exceeded.

    def __init__(self, max_size = 100):
        self.max_size = max_size
        self.data = [None]*max_size
        self.size = 0

    def peek(self):
        """ Return smallest value in heap """
        return self.data[0]

    def swap(self, i, j):
        """ In place exchange two values with given indices """
        temp = self.data[i]
        self.data[i] = self.data[j]
        self.data[j] = temp

    def push(self, value):
        """ put a new value into the heap; adjust accordingly"""
        self.data[self.size] = value
        self.size += 1
        index = self.size - 1   # need to bubble this up
        while self.data[index] < self.data[above(index)]:
            self.swap(index, above(index))
            index = above(index)

    def pop(self):
        # TODO: something similar ...
        return 0


def main():
    h = Heap()        # make an empty one
    print "Making a heap with 10 numbers in it."
    for i in random.sample(range(100), 10):
        h.push(i)         # add a number to the heap
    
    value = h.peek()  # get smallest, no removal
    print "The smallest value is " + str(value)

    print "The 5 smallest are: ",
    for i in range(5):
        value = h.pop()   # remove smallest number
        print " " + str(value),
    print

main()