Return a+b

Array

for x in ar:
sum += x

### Basic 3:

Array Python

# Stupid Init
- result = [0,0]
# Append
- cars.append("Honda")
# Pop
- cars.pop(1)
# Remove
- cars.remove("Volvo")

If Python

If ...:
elif ...:
else:

### Basic 4:

File

if __name__ == '__main__':
fptr = open(os.environ['OUTPUT_PATH'], 'w')

a = list(map(int, input().rstrip().split()))

b = list(map(int, input().rstrip().split()))

result = compareTriplets(a, b)

fptr.write(' '.join(map(str, result)))
fptr.write('\n')

fptr.close()

### Basic 5:

For in For Abs different in 2D array

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

Abs in Python

abs (x)

### Basic 6:

Print

print (positiveRate)

Default: auto break line

To get float

x = float (y/z)

Print (float (y/z))

### Basic 8:

Print staircase

for i in range(n):
for j in range(n):
if j < n-i-1 :
print (" ", end ="")
elif j == n-1:
print ("#")
else :
print ("#", end ="")

Print staircase ver2

for x in range(n):
for y in range(n):
if y < m:
print (' ', end='')
elif y >= m:
print ('#', end='')
m-=1
print ('')

Print ln = print ("") Should not use print ("\n”) because of default line break

else:

## Note: should not use for x, cannot change value in array when using that way

2020-02-08

### Basic 10:

Given a string, , of length that is indexed from to , print its even-indexed and odd-indexed characters as space-separated strings on a single line (see the Sample below for more detail).

S = ""
ar = []
n = int(input())
for i in range (0,n):
s = input()
length = len(s)
for j in range (0,length):
if j%2 == 0:
print (s[j], end = "")
print (" ", end ="")
for j in range (0,length):
if j%2 != 0:
print (s[j], end = "")
print ("")

### Basic 11:

input to array:

arr = list(map(int, input().rstrip().split()))

Given an array, , of integers, print ‘s elements in reverse order as a single line of space-separated numbers.

for i in reversed(range(n)):
print(arr[i], end = " ")

### Basic 12:

sockMerchant how to count and pair socks in the store

def sockMerchant(n, ar):
ar.sort()
count = []
result = 0
append = ar.count(ar[0])
count.append(append)
for i in range(n-1):
if ar[i] != ar[i+1]:
append = ar.count(ar[i+1])
count.append(append)
for x in count:
result = result + x//2
return result

### Basic 13:

Counting Valleys

def countingValleys(n, s):
sum = flagDown = flagUp = 0
track = []
track.append(sum)
count = 0
for i in range (n):
if s[i] == "D":
sum = sum - 1
track.append(sum)
elif s[i] == "U":
sum = sum + 1
track.append(sum)
t = len(track)
for j in range(1, t):
if (track[j-1] < track[j]):
flagUp = 1
flagDown = 0
if (track[j-1] > track[j]):
flagDown = 1
flagUp = 0
if (track[j] == 0) and flagUp == 1:
count = count + 1
return count

### Basic 14:

Jumping on Cloud

def jumpingOnClouds(c):
i = 0
count = 0
while (i < n-2):
if c[i] == 0 and c[i+2] == 0:
i = i+2
count += 1
else:
i = i+1
count += 1
if (i==n-1):
count = count
else:
count = count + 1
return count

### Basic 15:

Repeated String:

def repeatedString(s, n):
count = countEach = countSpec = 0
newstr = modstr = ""
leng = len(s)
repeat = n // leng
mod = n % leng
if mod == 0:
countSpec = 0
elif mod == 1:
modstr = s[0]
if s[0] == 'a':
countSpec = 1
else:
strmod = mod - 1
modstr = s[0:strmod]
for i in range (mod):
if s[i] == "a":
countSpec += 1
for i in range (leng):
if s[i] == "a":
countEach += 1

count = countEach*repeat+countSpec
return count

### Basic 16:

Apple Trees

countApples = countOranges = 0
for i in range (m):
apples[i] = apples[i] + a
if apples[i] >= s and apples[i] <= t:
countApples += 1

for i in range (n):
oranges[i] = oranges[i] + b
if oranges[i] >= s and oranges[i] <= t:
countOranges += 1
print (countApples)
print (countOranges)

Note: just need to read description carefully and understand variables

### Basic 17:

Kangaroo

flag = count = 0
result = ""
if v1 <= v2:
flag = 0
else:
while (x1 <= x2):
x1 = x1 + v1
x2 = x2 + v2
if x1 == x2:
flag = 1
if flag == 1:
result = "YES"
else:
result = "NO"
return result

### Basic 18:

Dictionary

n = int(input().strip())
phonebook = {}
for i in range(n):
line = input()
k, v = line.split()
phonebook[k] = v

while True:
try:
number = input()
except EOFError:
break
if number in phonebook:
print("{}={}".format(number, phonebook[number]))
else:

Read input to line Split line to get specific value to specific Variables Dictionary init: Dic[key] = value

Print Dictionary: print("{}={}".format(number, phonebook[number]))

Reduce timeout: while, try except…

### Basic 19:

Recursive

def factorial(n):
if n == 1:
return 1
else:
return n * factorial(n-1)

### Basic 20:

2D Array, hourglassSum

#!/bin/python3

import math
import os
import random
import re
import sys

# Complete the hourglassSum function below.
def hourglassSum(arr):
max = arr[0][0] + arr[0][1] + arr[0][2] + arr[1][1] + arr[2][0] + arr[2][1] + arr[2][2]
for i in range (4):
for j in range (4):
sum = arr[i][j] + arr[i][j+1] + arr[i][j+2] + arr[i+1][j+1] + arr[i+2][j] + arr[i+2][j+1] + arr[i+2][j+2]
if sum > max:
max = sum
sum = 0
else:
sum = 0
return max

if __name__ == '__main__':
fptr = open(os.environ['OUTPUT_PATH'], 'w')

arr = []

for _ in range(6):
arr.append(list(map(int, input().rstrip().split())))

result = hourglassSum(arr)

fptr.write(str(result) + '\n')

fptr.close()

### Basic 21:

Rotate

def rotLeft(a, d):
b = []
for i in range (n):
t = (i+d)
if (t>=n):
t = t%n
b.append(a[t])
print (i, t)
return b