Selection Sort - CS50 Shorts

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LICENSE

CC BY-NC-SA 4.0
Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International Public License

David J. Malan

[rafatulalam]

My Python code for this sorting algorithm:

arr = [7, 6, 8, 2, 3, 1, 4, 5]

def selection_sort(arr):

start = 0
min = None; min_index = None

while(start < len(arr) - 1):

min = arr[start]
min_index = start

for i in range(start + 1, len(arr)):

if(min > arr[i]):
min = arr[i]
min_index = i

temp = arr[min_index]
arr[min_index] = arr[start]
arr[start] = temp
start += 1

return arr


print('Before Selection Sort : ', arr)
print('After Selection Sort : ', selection_sort(arr))

[annakudriavtseva]

guys, you are so great. wish i could be someone saying "this is cs50".

[Slimgoodie]

Instead of 0(n^2) and Ω(n^2), could the answer just be Θ(n^2), since that would cover the best and worst case?

[TheRedstoneTaco]

I thought it would take 2 minutes to code this but I got way too used to python.
:/

[allthingsthoughchris]

The pause when waiting for us was disturbing

[gomezmario.f]

function SelectionSort(array){
for(var i = 0; i < array.length; i++){

console.log("at value => ", array[i])
var smallest = array[i];
for(var j = i; j < array.length; j++){
j)
console.log("testing " +array[i] + " with "+ array[j])
if(smallest <= array[j]){
console.log(array[i] + "value is already smaller or d same")
console.log(" Not swapping")
continue;
}
console.log("value is NOT smaller, swapping and continueing to next value");
var old = array[i];
array[i] = array[j];
array[j] = old;
console.log("swaped, smallest is currently" + array[i])
console.log(array)
}
// array[i] = smallest;
console.log("swapping")
console.log(array)
}
console.log("final =>" + array)
}

SelectionSort([5, 4, 33, 2, 33, 33, 2, 1, 100, 34, 45]);
// How did i do?

[andreasv]

So I make the array I search for smaller in each step right? So I don't search in the already sorted part (and same in bubble sort?)

[rxtez]

do you need pointers to implement this

[brandybabyyy]

sorry, why is it not n!, ie n(n-1)(n-2)...

[raywu]

brain.exe stopped working








I did understand eventually though

[JorgeArmandoBM]

Python:

def (v):

l = 0
r = len(v)

for i in range(l, r):

for j in range(i+1, r):

print(v[i], '>', v[j], v[i] > v[j])

if v[i] > v[j]:

v[i], v[j] = v[j], v[i]
print(v)


return v

[lowrl]

Doug how could you be so prejudice!? You're all about blue, red, and green but what about all of the other colors. Why do you hate purple?! Who hurt you Doug and what does purple have to do with it?