Design a Data Structure with insert (key,value),get,delete & get last accessed key operations with each...
I can create a class with members map to store key,value and stack
to maintain the history of operations performed onto the class
objects. However, the tricky part is last key retrieval in O(1)-
if a key has been deleted, I would require to search the entire
stack for valid key in the map, which will be of O(n) in the worst case.
For instance
insert(a,1)
insert(b,1)
get(a) -> output 1
get_last_key -> output a delete(a)
get_last_key -> output b
Is there a better way of designing the structure for better performance?
algorithm data-structures
edited Nov 13 '18 at 17:32
user6910411
33.6k976100
asked Nov 13 '18 at 15:36
DreamerDreamer
61
|
show 1 more comment
I can create a class with members map to store key,value and stack
to maintain the history of operations performed onto the class
objects. However, the tricky part is last key retrieval in O(1)-
if a key has been deleted, I would require to search the entire
stack for valid key in the map, which will be of O(n) in the worst case.
For instance
insert(a,1)
insert(b,1)
get(a) -> output 1
get_last_key -> output a delete(a)
get_last_key -> output b
Is there a better way of designing the structure for better performance?
algorithm data-structures
edited Nov 13 '18 at 17:32
user6910411
33.6k976100
asked Nov 13 '18 at 15:36
DreamerDreamer
61
1
Define "performance". Everything is a trade-off. If you are worried about run time then you trade-off with space. But this is not quite on-topic for SO.
– jdv
Nov 13 '18 at 15:41
@jdv O(1) for all the operations
– Dreamer
Nov 13 '18 at 15:43
My point is that asking SO to design some unknown program for you is not on-topic.
– jdv
Nov 13 '18 at 15:44
space isn't the constraint.
– Dreamer
Nov 13 '18 at 15:44
1
Note that for each key, you only care about most recent access. Keeping a history of more than that is wasteful. If you use a set of keys in history, you can reduce the O(n) to O(log keys). If you use a linked list + a map for key -> linked list pointer, you can make that into O(1)
– juvian
Nov 13 '18 at 16:19
|
show 1 more comment
I can create a class with members map to store key,value and stack
to maintain the history of operations performed onto the class
objects. However, the tricky part is last key retrieval in O(1)-
if a key has been deleted, I would require to search the entire
stack for valid key in the map, which will be of O(n) in the worst case.
For instance
insert(a,1)
insert(b,1)
get(a) -> output 1
get_last_key -> output a delete(a)
get_last_key -> output b
Is there a better way of designing the structure for better performance?
algorithm data-structures
edited Nov 13 '18 at 17:32
user6910411
33.6k976100
asked Nov 13 '18 at 15:36
DreamerDreamer
61
I can create a class with members map to store key,value and stack
to maintain the history of operations performed onto the class
objects. However, the tricky part is last key retrieval in O(1)-
if a key has been deleted, I would require to search the entire
stack for valid key in the map, which will be of O(n) in the worst case.
For instance
insert(a,1)
insert(b,1)
get(a) -> output 1
get_last_key -> output a delete(a)
get_last_key -> output b
Is there a better way of designing the structure for better performance?
algorithm data-structures
algorithm data-structures
edited Nov 13 '18 at 17:32
user6910411
33.6k976100
asked Nov 13 '18 at 15:36
DreamerDreamer
61
edited Nov 13 '18 at 17:32
user6910411
33.6k976100
asked Nov 13 '18 at 15:36
DreamerDreamer
61
edited Nov 13 '18 at 17:32
user6910411
33.6k976100
edited Nov 13 '18 at 17:32
user6910411
33.6k976100
edited Nov 13 '18 at 17:32
user6910411
33.6k976100
33.6k976100
asked Nov 13 '18 at 15:36
DreamerDreamer
61
asked Nov 13 '18 at 15:36
DreamerDreamer
61
asked Nov 13 '18 at 15:36
DreamerDreamer
61
61
1
Define "performance". Everything is a trade-off. If you are worried about run time then you trade-off with space. But this is not quite on-topic for SO.
– jdv
Nov 13 '18 at 15:41
@jdv O(1) for all the operations
– Dreamer
Nov 13 '18 at 15:43
My point is that asking SO to design some unknown program for you is not on-topic.
– jdv
Nov 13 '18 at 15:44
space isn't the constraint.
– Dreamer
Nov 13 '18 at 15:44
1
Note that for each key, you only care about most recent access. Keeping a history of more than that is wasteful. If you use a set of keys in history, you can reduce the O(n) to O(log keys). If you use a linked list + a map for key -> linked list pointer, you can make that into O(1)
– juvian
Nov 13 '18 at 16:19
|
show 1 more comment
1
Define "performance". Everything is a trade-off. If you are worried about run time then you trade-off with space. But this is not quite on-topic for SO.
– jdv
Nov 13 '18 at 15:41
@jdv O(1) for all the operations
– Dreamer
Nov 13 '18 at 15:43
My point is that asking SO to design some unknown program for you is not on-topic.
– jdv
Nov 13 '18 at 15:44
space isn't the constraint.
– Dreamer
Nov 13 '18 at 15:44
1
Note that for each key, you only care about most recent access. Keeping a history of more than that is wasteful. If you use a set of keys in history, you can reduce the O(n) to O(log keys). If you use a linked list + a map for key -> linked list pointer, you can make that into O(1)
– juvian
Nov 13 '18 at 16:19
1
1
Define "performance". Everything is a trade-off. If you are worried about run time then you trade-off with space. But this is not quite on-topic for SO.
– jdv
Nov 13 '18 at 15:41
Define "performance". Everything is a trade-off. If you are worried about run time then you trade-off with space. But this is not quite on-topic for SO.
– jdv
Nov 13 '18 at 15:41
@jdv O(1) for all the operations
– Dreamer
Nov 13 '18 at 15:43
@jdv O(1) for all the operations
– Dreamer
Nov 13 '18 at 15:43
My point is that asking SO to design some unknown program for you is not on-topic.
– jdv
Nov 13 '18 at 15:44
My point is that asking SO to design some unknown program for you is not on-topic.
– jdv
Nov 13 '18 at 15:44
space isn't the constraint.
– Dreamer
Nov 13 '18 at 15:44
space isn't the constraint.
– Dreamer
Nov 13 '18 at 15:44
1
1
Note that for each key, you only care about most recent access. Keeping a history of more than that is wasteful. If you use a set of keys in history, you can reduce the O(n) to O(log keys). If you use a linked list + a map for key -> linked list pointer, you can make that into O(1)
– juvian
Nov 13 '18 at 16:19
Note that for each key, you only care about most recent access. Keeping a history of more than that is wasteful. If you use a set of keys in history, you can reduce the O(n) to O(log keys). If you use a linked list + a map for key -> linked list pointer, you can make that into O(1)
– juvian
Nov 13 '18 at 16:19
|
show 1 more comment
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1
Define "performance". Everything is a trade-off. If you are worried about run time then you trade-off with space. But this is not quite on-topic for SO.
– jdv
Nov 13 '18 at 15:41
@jdv O(1) for all the operations
– Dreamer
Nov 13 '18 at 15:43
My point is that asking SO to design some unknown program for you is not on-topic.
– jdv
Nov 13 '18 at 15:44
space isn't the constraint.
– Dreamer
Nov 13 '18 at 15:44
1
Note that for each key, you only care about most recent access. Keeping a history of more than that is wasteful. If you use a set of keys in history, you can reduce the O(n) to O(log keys). If you use a linked list + a map for key -> linked list pointer, you can make that into O(1)
– juvian
Nov 13 '18 at 16:19