Binary Search Tree find successor of given key (where the key does not have to be in tree)












0














How would I change the following code I have written to account for an inputed pair k that is not in the bst? In other words, how would I find the successor of a key in a binary search tree that does not exist in it?



public Record getSuccessor(Pair k, Node root) {

if(root == null) {
return null;
}

if(k.compareTo(root.getNodeRecord().getKey()) == 0) {
if(root.getRightChild() != null) {
return getSmallest(root.getRightChild());
}
else {
return root.getParent().getNodeRecord();
}
}
else {
Record left = getSuccessor(k, root.getLeftChild());
if(left != null) {
return left;
}
return getSuccessor(k, root.getRightChild());
}
}









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  • could you give an example? for instance, what if the key is 2 and you have 2, 4, 5, 6, 8 in BST. which value do you imply by successor not in bst? by the way there is a mismatch between the title of your question (predecessor) and question itself (successor)
    – mangusta
    Nov 12 '18 at 1:58












  • @mangusta for example, if the key is 5 and we have 8, 3, 1, 6, 4, 7 ,10, 14 and 3 is BST, the successor to 5 (although 5 is not in the BST) would be 6
    – Ben Tilden
    Nov 12 '18 at 2:41










  • have you tried in-order DFS traversal? it is going to give you all bst elements in increasing order so that you may find the successor of any key in linear time
    – mangusta
    Nov 12 '18 at 3:05








  • 1




    ah, seems that the traversal is not necessary at all. you simply save the current node everytime before going left, and then there are several possible cases: 1. you reached the key but it doesn't have a right child. then successor is the key you saved on going left last time. 2. you reached the key and it has a right child, then you move right and then continuously move left until you reach leaf node. 3. the key is not in tree. then you end up with some leaf node and its successor is the key you saved on going left last time
    – mangusta
    Nov 12 '18 at 3:40


















0














How would I change the following code I have written to account for an inputed pair k that is not in the bst? In other words, how would I find the successor of a key in a binary search tree that does not exist in it?



public Record getSuccessor(Pair k, Node root) {

if(root == null) {
return null;
}

if(k.compareTo(root.getNodeRecord().getKey()) == 0) {
if(root.getRightChild() != null) {
return getSmallest(root.getRightChild());
}
else {
return root.getParent().getNodeRecord();
}
}
else {
Record left = getSuccessor(k, root.getLeftChild());
if(left != null) {
return left;
}
return getSuccessor(k, root.getRightChild());
}
}









share|improve this question
























  • could you give an example? for instance, what if the key is 2 and you have 2, 4, 5, 6, 8 in BST. which value do you imply by successor not in bst? by the way there is a mismatch between the title of your question (predecessor) and question itself (successor)
    – mangusta
    Nov 12 '18 at 1:58












  • @mangusta for example, if the key is 5 and we have 8, 3, 1, 6, 4, 7 ,10, 14 and 3 is BST, the successor to 5 (although 5 is not in the BST) would be 6
    – Ben Tilden
    Nov 12 '18 at 2:41










  • have you tried in-order DFS traversal? it is going to give you all bst elements in increasing order so that you may find the successor of any key in linear time
    – mangusta
    Nov 12 '18 at 3:05








  • 1




    ah, seems that the traversal is not necessary at all. you simply save the current node everytime before going left, and then there are several possible cases: 1. you reached the key but it doesn't have a right child. then successor is the key you saved on going left last time. 2. you reached the key and it has a right child, then you move right and then continuously move left until you reach leaf node. 3. the key is not in tree. then you end up with some leaf node and its successor is the key you saved on going left last time
    – mangusta
    Nov 12 '18 at 3:40
















0












0








0







How would I change the following code I have written to account for an inputed pair k that is not in the bst? In other words, how would I find the successor of a key in a binary search tree that does not exist in it?



public Record getSuccessor(Pair k, Node root) {

if(root == null) {
return null;
}

if(k.compareTo(root.getNodeRecord().getKey()) == 0) {
if(root.getRightChild() != null) {
return getSmallest(root.getRightChild());
}
else {
return root.getParent().getNodeRecord();
}
}
else {
Record left = getSuccessor(k, root.getLeftChild());
if(left != null) {
return left;
}
return getSuccessor(k, root.getRightChild());
}
}









share|improve this question















How would I change the following code I have written to account for an inputed pair k that is not in the bst? In other words, how would I find the successor of a key in a binary search tree that does not exist in it?



public Record getSuccessor(Pair k, Node root) {

if(root == null) {
return null;
}

if(k.compareTo(root.getNodeRecord().getKey()) == 0) {
if(root.getRightChild() != null) {
return getSmallest(root.getRightChild());
}
else {
return root.getParent().getNodeRecord();
}
}
else {
Record left = getSuccessor(k, root.getLeftChild());
if(left != null) {
return left;
}
return getSuccessor(k, root.getRightChild());
}
}






search tree binary






share|improve this question















share|improve this question













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edited Nov 12 '18 at 2:46









Gene

37.5k44274




37.5k44274










asked Nov 12 '18 at 0:48









Ben Tilden

496




496












  • could you give an example? for instance, what if the key is 2 and you have 2, 4, 5, 6, 8 in BST. which value do you imply by successor not in bst? by the way there is a mismatch between the title of your question (predecessor) and question itself (successor)
    – mangusta
    Nov 12 '18 at 1:58












  • @mangusta for example, if the key is 5 and we have 8, 3, 1, 6, 4, 7 ,10, 14 and 3 is BST, the successor to 5 (although 5 is not in the BST) would be 6
    – Ben Tilden
    Nov 12 '18 at 2:41










  • have you tried in-order DFS traversal? it is going to give you all bst elements in increasing order so that you may find the successor of any key in linear time
    – mangusta
    Nov 12 '18 at 3:05








  • 1




    ah, seems that the traversal is not necessary at all. you simply save the current node everytime before going left, and then there are several possible cases: 1. you reached the key but it doesn't have a right child. then successor is the key you saved on going left last time. 2. you reached the key and it has a right child, then you move right and then continuously move left until you reach leaf node. 3. the key is not in tree. then you end up with some leaf node and its successor is the key you saved on going left last time
    – mangusta
    Nov 12 '18 at 3:40




















  • could you give an example? for instance, what if the key is 2 and you have 2, 4, 5, 6, 8 in BST. which value do you imply by successor not in bst? by the way there is a mismatch between the title of your question (predecessor) and question itself (successor)
    – mangusta
    Nov 12 '18 at 1:58












  • @mangusta for example, if the key is 5 and we have 8, 3, 1, 6, 4, 7 ,10, 14 and 3 is BST, the successor to 5 (although 5 is not in the BST) would be 6
    – Ben Tilden
    Nov 12 '18 at 2:41










  • have you tried in-order DFS traversal? it is going to give you all bst elements in increasing order so that you may find the successor of any key in linear time
    – mangusta
    Nov 12 '18 at 3:05








  • 1




    ah, seems that the traversal is not necessary at all. you simply save the current node everytime before going left, and then there are several possible cases: 1. you reached the key but it doesn't have a right child. then successor is the key you saved on going left last time. 2. you reached the key and it has a right child, then you move right and then continuously move left until you reach leaf node. 3. the key is not in tree. then you end up with some leaf node and its successor is the key you saved on going left last time
    – mangusta
    Nov 12 '18 at 3:40


















could you give an example? for instance, what if the key is 2 and you have 2, 4, 5, 6, 8 in BST. which value do you imply by successor not in bst? by the way there is a mismatch between the title of your question (predecessor) and question itself (successor)
– mangusta
Nov 12 '18 at 1:58






could you give an example? for instance, what if the key is 2 and you have 2, 4, 5, 6, 8 in BST. which value do you imply by successor not in bst? by the way there is a mismatch between the title of your question (predecessor) and question itself (successor)
– mangusta
Nov 12 '18 at 1:58














@mangusta for example, if the key is 5 and we have 8, 3, 1, 6, 4, 7 ,10, 14 and 3 is BST, the successor to 5 (although 5 is not in the BST) would be 6
– Ben Tilden
Nov 12 '18 at 2:41




@mangusta for example, if the key is 5 and we have 8, 3, 1, 6, 4, 7 ,10, 14 and 3 is BST, the successor to 5 (although 5 is not in the BST) would be 6
– Ben Tilden
Nov 12 '18 at 2:41












have you tried in-order DFS traversal? it is going to give you all bst elements in increasing order so that you may find the successor of any key in linear time
– mangusta
Nov 12 '18 at 3:05






have you tried in-order DFS traversal? it is going to give you all bst elements in increasing order so that you may find the successor of any key in linear time
– mangusta
Nov 12 '18 at 3:05






1




1




ah, seems that the traversal is not necessary at all. you simply save the current node everytime before going left, and then there are several possible cases: 1. you reached the key but it doesn't have a right child. then successor is the key you saved on going left last time. 2. you reached the key and it has a right child, then you move right and then continuously move left until you reach leaf node. 3. the key is not in tree. then you end up with some leaf node and its successor is the key you saved on going left last time
– mangusta
Nov 12 '18 at 3:40






ah, seems that the traversal is not necessary at all. you simply save the current node everytime before going left, and then there are several possible cases: 1. you reached the key but it doesn't have a right child. then successor is the key you saved on going left last time. 2. you reached the key and it has a right child, then you move right and then continuously move left until you reach leaf node. 3. the key is not in tree. then you end up with some leaf node and its successor is the key you saved on going left last time
– mangusta
Nov 12 '18 at 3:40



















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