def binarysearch(a,num): #function definition with its parameters 'a' is the inputlist #and 'num' number to be found first=0 #initially the first position is zero last=len(a)-1 #initially the last position is the total length of the inputlist-1 found=False #boolean value to indicate if the number to be searched is found or not. while first<=last and not found: midpoint=(first+last)//2 #dividing the inputlist into two halves and comparing the number to be found with the midpoint. if a[midpoint]==num: #If the number to be found is equal to the midpoint returns the position. found=True else: if num<a[midpoint]: #if the number to be found is less than the midpoint #then the first half of the divided input list is taken for further computation. last=midpoint-1 #by assigning the last number of the first half(number before the midpoint) to the variable last. else: first=midpoint+1 #if the number to be found is greater than the midpoint #then the second half of the divided input list is taken for further computation. #by assigning the first number of the second half(number following the midpoint) to the variable first. return midpoint #returns the position of the number found in the list. numlist=[1, 23, 5, 6, 7, 8, 10, 12, 13, 15, 16, 18, 19, 20, 22] #List of inputs print "Found number 19 at the position",(binarysearch(numlist, 19)) #Printing the position of the number to be found by a function call. #The function binarysearch is called along with its parameters, inputlist #and the number to be found.
Found number 19 at the position 12
#To perform insertionsort def sort_insertion(inputlist): for i in range(1,len(inputlist)): val_current = inputlist[i] pos = i # check backwards through sorted list for proper pos of val_current while((pos > 0) and (inputlist[pos-1] > val_current)): inputlist[pos] = inputlist[pos-1] pos = pos-1 if pos != i: inputlist[pos] = val_current print(inputlist) return inputlist inputlist = [3,2,4,1,5] print sort_insertion(inputlist)
[2, 3, 4, 1, 5] [1, 2, 3, 4, 5] [1, 2, 3, 4, 5]