I am working on the following Python list exercise from codingbat.com:
Given an array of ints, return the sum of the first 2 elements in the array. If the array length is less than 2, just sum up the elements that exist, returning 0 if the array is length 0. Examples:
sum2[[1, 2, 3]] → 3 sum2[[1, 1]] → 2 sum2[[1, 1, 1, 1]] → 2
My solution below works:
def sum2[nums]:
if len[nums]>=2:
return nums[0] + nums[1]
elif len[nums]==1:
return nums[0]
return 0
But I wonder if there's any way to solve the problem with fewer conditional statements.
jonrsharpe
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asked Jul 18, 2014 at 13:59
2
There is. Two elements of the solution - builtin function
sum and lists's slices:
>>> sum[[1,2,3][:2]]
3
>>> sum[[1,1,1,1][:2]]
2
>>> sum[[1,1][:2]]
2
>>> sum[[1][:2]]
1
>>> sum[[][:2]]
0
answered Jul 18, 2014 at 14:02
Roman BodnarchukRoman Bodnarchuk
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5
If you can't use sum, one possible solution uses exceptions:
totalsum = 0
try:
totalsum += nums[0]
totalsum += nums[1]
except IndexError:
pass
return totalsum
Catch the error and short-circuit the summation if an element doesn't exist. Easier to ask forgiveness than permission, as they say.
answered Jul 18, 2014 at 14:04
TheSoundDefenseTheSoundDefense
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4
try this:
def sum2[nums]:
if len[nums] == 1:
return nums[0]
else:
return sum[nums [:2]]
answered May 4, 2017 at 18:41
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Given a list of numbers, write a Python program to find the sum of all the elements in the list.
Example:
Input: [12, 15, 3, 10] Output: 40
Input: [17, 5, 3, 5] Output: 30
Example #1:
Python3
total = 0
list1 = [11, 5, 17, 18, 23]
for ele in range[0, len[list1]]:
total = total + list1[ele]
print["Sum of all elements in given list: ", total]
Output
Sum of all elements in given list: 74
Example #2 : Using while[] loop
Python3
total = 0
ele = 0
list1 = [11, 5, 17, 18, 23]
while[ele < len[list1]]:
total = total + list1[ele]
ele += 1
print["Sum of all elements in given list: ", total]
Output:
Sum of all elements in given list: 74
Example #3: Recursive way
Python3
list1 = [11, 5, 17, 18, 23]
def sumOfList[list, size]:
if [size == 0]:
return 0
else:
return list[size - 1] +
sumOfList[list, size - 1]
total = sumOfList[list1, len[list1]]
print["Sum of all elements in given list: ", total]
Output
Sum of all elements in given list: 74
Example #4: Using sum[] method
Python3
list1 =
[11, 5, 17, 18, 23]
total = sum[list1]
print["Sum of all elements in given list: ", total]
Output:
Sum of all elements in given list: 74
Example 5: Using add[] function of operator module
First we have to import the operator module then using the add[] function of operator module adding the all values in the list.
Python3
from operator import*
list1 = [12, 15, 3, 10]
result = 0
for i in list1:
result = add[i, 0]+result
print[result]
Method 6: Using enumerate function
Python3
list1 =
[12, 15, 3, 10];s=0
for i,a in enumerate[list1]:
s+=a
print[s]
Method 7: Using list comprehension
Python3
list1 = [12, 15, 3, 10]
s=[i for
i in list1]
print[sum[s]]
Method 8: Using lambda function
Python3
list1 = [12, 15, 3, 10]
print[sum[list[filter[lambda x: [x],list1]]]]
Method: Using add operator
Python3
import
operator
list1 = [12, 15, 3, 10] ;s=0
for i in list1:
s=s+operator.add[0,i]
print[s]