not explicitly create subsequences indeeda subsequence of the input sequence is implicitly represented by range of positions specified by left-most index and right-most index the divide step is performed by scanning the array simultaneously from forward and from backwardswapping pairs of elements that are in reverse orderas shown in figure when these two indices "meet,subarrays and are on opposite sides of the meeting point the algorithm completes by recurring on these two subarrays in-place quick-sort reduces the running time caused by the creation of new sequences and the movement of elements between them by constant factor we show java version of in-place quick-sort in code fragment figure divide step of in-place quick-sort index scans the sequence from left to rightand index scans the sequence from right to left swap is performed when is at an element larger than the pivot