DSA Slides — 100 Algorithms

for i in range(len(arr)):
    if arr[i] == target:
        return i
return -1

while left <= right:
    mid = left + (right - left) // 2
    if arr[mid] == target:
        return mid
    elif arr[mid] < target:
        left = mid + 1
    else:
        right = mid - 1

while left <= right:
    mid1 = left + (right - left) // 3
    mid2 = right - (right - left) // 3

    if arr[mid1] == target:
        return mid1
    elif arr[mid2] == target:
        return mid2
    elif target < arr[mid1]:
        right = mid1 - 1
    elif target > arr[mid2]:
        left = mid2 + 1
    else:
        left = mid1 + 1
        right = mid2 - 1

step = int(sqrt(n))
prev = 0
while prev < n and arr[min(step, n)-1] < target:
    prev = step
    step += int(sqrt(n))
    if prev >= n:
        break
# then linear search in block

while low <= high and target >= arr[low] and target <= arr[high]:
    pos = low + int(((target-arr[low])*(high-low)) / (arr[high]-arr[low]))
    if arr[pos] == target:
        return pos
    elif arr[pos] < target:
        low = pos + 1
    else:
        high = pos - 1

if arr[0] == target:
    return 0
index = 1
while index < n and arr[index] <= target:
    index *= 2
# then binary search in range [index/2, min(index,n-1)]

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

for i in range(len(arr)):
    min_idx = i
    for j in range(i+1, len(arr)):
        if arr[j] < arr[min_idx]:
            min_idx = j
    arr[i], arr[min_idx] = arr[min_idx], arr[i]

for i in range(1, len(arr)):
    key = arr[i]
    j = i - 1
    while j >= 0 and arr[j] > key:
        arr[j+1] = arr[j]; j -= 1
    arr[j+1] = key

# after splitting L and R
i = j = k = 0
while i < len(L) and j < len(R):
    if L[i] < R[j]: arr[k] = L[i]; i += 1
    else: arr[k] = R[j]; j += 1
    k += 1
arr[k:] = L[i:] + R[j:]

pivot = arr[high]
i = low - 1
for j in range(low, high):
    if arr[j] <= pivot:
        i += 1; arr[i], arr[j] = arr[j], arr[i]
arr[i+1], arr[high] = arr[high], arr[i+1]
return i+1

largest = root
left = 2*root + 1
right = 2*root + 2
if left < n and arr[left] > arr[largest]: largest = left
if right < n and arr[right] > arr[largest]: largest = right
if largest != root:
    arr[root], arr[largest] = arr[largest], arr[root]
    heapify(n, largest)

count = [0] * (max_val + 1)
for x in arr: count[x] += 1
for i in range(1, len(count)): count[i] += count[i-1]
# build output by placing items using counts (stable)

exp = 1
while max_val//exp > 0:
    # stable counting sort by digit (arr[i]//exp % 10)
    exp *= 10

gap = n//2
while gap > 0:
    for i in range(gap, n):
        temp = arr[i]
        j = i
        while j >= gap and arr[j-gap] > temp:
            arr[j] = arr[j-gap]
            j -= gap
        arr[j] = temp
    gap //= 2

def fib(n):
    if n < 2: return n
    return fib(n-1) + fib(n-2)

def fact(n):
    if n <= 1: return 1
    return n * fact(n-1)

def inorder(node):
    if node:
        inorder(node.left)
        print(node.val)
        inorder(node.right)

from collections import deque
q = deque([start]); visited.add(start)
while q:
    node = q.popleft()
    for nbr in graph[node]:
        if nbr not in visited:
            visited.add(nbr); q.append(nbr)

def dfs(u):
    visited.add(u)
    for v in graph[u]:
        if v not in visited: dfs(v)

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statementldmbkdsbkksb
    dzlbk zdk 
    ,blxmbk xzkbb
    dzmbk
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement

if condition:
    statement
else:
    other_statement