Algorithms

Question 1

Bubble sort

Answer 1

for i in range(0, len(arr)):
for j in range(0, len(arr) -1):
if arr[j] > arr[j+1]:
arr[j], arr[j+1] = arr[j+1], arr[j]
return arr

Question 2

Dictionary build

Answer 2

d = {}
for i in str:
if i in d:
d[i] += 1
else:
d[i] = 1
return d

Question 3

Merge sort

Answer 3

if len(arr) > 1:
mid = len(arr) // 2
left_half = arr[:mid]
right_half = arr[mid:]

merge_sort(left_half)
merge_sort(right_half)

i = j = k = 0

while i < len(left_half) and j < len(right_half):
if left_half[i] < right_half[j]:
arr[k] = left_half[i]
i += 1
else:
arr[k] = right_half[j]
j += 1
k += 1
while i < len(left_half):
arr[k] = left_half[i]
i += 1
k += 1
while j < len(right_half):
arr[k] = right_half[j]
j += 1
k += 1

Question 4

Two_sum

Answer 4

def two_sum(nums, target):
num_dict = {}
for i, num in enumerate():
complement = target - num
if complement in num_dict:
return [num_dict[complement], i]
num_dic[num] = i
return None