Sprint/Python_DSA_Day1.txt at main · Aayushdh99/Sprint · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
# SEARCHING in sorted list/array
# Binary Search Recursive
def bs_recursive(nums, element, left, right):
    if right>=left:
        mid = left + (right-left)//2
        if nums[mid] == element:
            return mid
        if nums[mid] < element:
            return bs_recursive(nums, element, mid+1, right)
        return bs_recursive(nums, element, left, mid-1)
    return-1

def bs(nums, element):
    left, right = 0, len(nums)-1
    while(left<=right):
        mid = left + (right-left)//2
        if nums[mid] == element:
            return mid
        elif nums[mid] < element:
            left = mid+1
        else:
            right = mid-1
    return -1

nums = [1,3,4,5,7,9,10,13,14]
element = 13
#print(bs_recursive(nums, element, 0, len(nums)-1))
#print(bs(nums, element))


# SORTING

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

def selection(arr):
    for i in range(len(arr)-1):
        min = i
        for j in range(i+1, len(arr)):
            if arr[j] < arr[min]:
                min = j

        if min != i:
            arr[min], arr[i] = arr[i], arr[min]

    return arr

def insertion(arr):
    for i in range(1, len(arr)):
        value_to_sort = arr[i]
        while arr[i-1] > value_to_sort and i>0:
            arr[i-1], arr[i] = arr[i], arr[i-1]
            i = i-1
    return arr


#arr = [64, 34, 25, 12, 22, 11, 90]
#print(insertion(arr))
import random

def quick(arr):
    if len(arr) <= 1:
        return arr
    else:
        pivot = arr.pop()

    left_array = []
    right_array = []

    for item in arr:
        if item < pivot:
            left_array.append(item)
        else:
            right_array.append(item)

    return quick(left_array)+[pivot]+quick(right_array)

#arr = [12,12,12,12, 12, 22, 11, 90]
#print(quick(arr))


# Quick Sorrt basic method (pivot is random here)

import random

def partition(arr, left, right):
  if len(arr)>1:
    index = random.randint(left, right)
    if arr[index] != arr[right]:
      arr[index], arr[right] = arr[right], arr[index]

  i = left-1
  pivot = arr[right]

  for j in range(left, right):
    if arr[j] < pivot:
      i+=1
      arr[i], arr[j] = arr[j], arr[i]

  arr[i+1], arr[right] = arr[right], arr[i+1]
  return i+1

def quicksort(arr, left, right):
  if len(arr) <=1:
    return arr
  if left<right:
    pi = partition(arr, left, right)

    quicksort(arr, left, pi-1)
    quicksort(arr, pi+1, right)

arr = [10, 7, 8, 9, 1, 5]
n = len(arr)
quicksort(arr, 0, n-1)
print(arr)


## Find k largest element in unsorted array O(n)- Quickselect
import random

def partition(arr, left, right):
  if len(arr)>1:
    index = random.randint(left, right)
    if arr[index] != arr[right]:
      arr[index], arr[right] = arr[right], arr[index]

  i = left-1
  pivot = arr[right]

  for j in range(left, right):
    if arr[j] < pivot:
      i+=1
      arr[i], arr[j] = arr[j], arr[i]

  arr[i+1], arr[right] = arr[right], arr[i+1]
  return i+1

def quicksort(arr, left, right, k):
    while left < right:
        pi = partition(arr, left, right)
        if pi == k:
            break
        elif pi < k:
            left = pi+1
        else:
            right = pi-1

    return arr[k]


arr = [10, 7, 8, 9, 1, 5]
n = len(arr)
k = 1
print(quicksort(arr, 0, n-1, k-1))