Example: what is time complexity of insertion sort Time Complexity is : If the inversion count is O ( n ) , then the time complexity of insertion sort is O ( n ) . Some Facts about insertion sort : 1. Simple implementation : Jon Bentley shows a three - line C version , and a five - line optimized version [ 1 ] 2. Efficient for ( quite ) small data sets , much like other quadratic sorting algorithms 3. More efficient in practice than most other simple quadratic ( i . e . , O ( n2 ) ) algorithms such as selection sort or bubble sort 4. Adaptive , i . e . , efficient for data sets that are already substantially sorted : the time complexity is O ( kn ) when each element in the input is no more than k places away from its sorted position 5. Stable ; i . e . , does not change the relative order of elements with equal keys 6. In - place ; i . e . , only requires a constant amount O ( 1 ) of additional memory space Online ; i . e . , can sort a list a