Why is bubble sort O(n^2)?

Question

for (int front = 1; front < intArray.length; front++)
{
    for (int i = 0; i  < intArray.length - front; i++)
    {
        if (intArray[i] > intArray[i +          


        

Answer 1

Your inner loop is iterating, IN TOTAL, as you said n + (n-1) + (n-2) + (n-3) + ... + 1 times. So it is O(n + (n-1) + (n-2) + (n-3) + ... + 1) = O(n(n+1)/2) = O(n^2)