list operation worst case list( ( (nv[ix ( append(xo(nv extend(wo(nv insert(xo(nv pop( (ntraversal (ntable worst case time-complexities for the more common list operations list traversal sequence traversal accesses the individual itemsone after the otherin order to perform some operation on every item python provides the built-in iteration for the list structurewhich accesses the items in sequential order starting with the first item consider the following code segmentwhich iterates over and computes the sum of the integer values in listsum for value in valuelist sum sum value to determine the order of complexity for this simple algorithmwe must first look at the internal implementation of the traversal iteration over the contiguous elements of - arraywhich is used to store the elements of listrequires count-controlled loop with an index variable whose value ranges over the indices of the subarray the list iteration above is equivalent to the followingsum for in rangelen(valuelistsum sum valuelist[iassuming the sequence contains itemsit' obvious the loop performs iterations since all of the operations within the loop only require constant timeincluding the element access operationa complete list traversal requires (ntime notethis time establishes minimum required for complete list traversal it can actually be higher if any operations performed during each iteration are worse than constant timeunlike this example list allocation creating listlike the creation of any objectis considered an operation whose time-complexity can be analyzed there are two techniques commonly used to