Lecture Notes on 11 November 2009

# Binary Search function that searches for x in a list a
# It returns the position of x if it finds it or -1 if it does not.
def binarySearch (a, x):
  lo = 0
  hi = len(a) - 1

  while (lo <= hi):
    mid = (lo + hi) /2
    if (x < a[mid]):
      hi = mid - 1
    elif (x > a[mid]):
      lo = mid + 1
    else:
      return mid

  return -1

# Sorts a list a by finding minimums and swapping them elements in the list
def selectionSort (a):
  limit = len(a)
  for i in range (limit - 1):
    min = a[i]
    minIdx = i
    for j in range (i + 1, limit):
      if (a[j] < min):
        min = a[j]
	minIdx = j
    a[minIdx] = a[i]
    a[i] = min

def main():
  a = [9, 1, 8, 2, 3, 7, 4, 6, 5]
  print a
  selectionSort (a)
  print a

main()