O(1)
Constant
Array access, hash table lookup
O(log n)
Logarithmic
Binary search
O(n)
Linear
Linear search, single loop
O(n log n)
Linearithmic
Merge sort, quicksort (average)
O(n²)
Quadratic
Nested loops, bubble sort
O(n³)
Cubic
Triple nested loops
O(2ⁿ)
Exponential
Fibonacci (naive recursion)
O(n!)
Factorial
Generating all permutations