In Place Algorithms
I n-Place Algorithms are required to solve those problems which have limited memory constraints. You are not allowed to use extra memory and hence all operations need to be performed on the original data structures themselves. Usually, the algorithms should use O(1), constant memory. You are allowed to declare variables but not complete data structures. For example, you are given an array [1,2,2,4] and you need to delete all values which are equal to 2. One approach could be by checking each element of the array. If it is 2 then skip otherwise store the value in a new array and at the end of the loop[ when traversed every element of array ], return the new array. But this approach is not In-Place as it requires O(n) memory [ Worst case when no element of given value in array ]. For an In-Place algorithm we would need to delete the elements with value in the original array and then return the original array as the answer to the problem.