Doubly-linked list/Element removal: Difference between revisions
Doubly-linked list/Element removal (view source)
Revision as of 06:37, 27 September 2020
, 3 years ago→{{header|Julia}}
(Added Algol W) |
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=={{header|Julia}}==
Uses code from [[Doubly-Linked List (traversal)]]
<lang julia>mutable struct DLNode{T}
value::T
pred::Union{DLNode{T}, Nothing}
succ::Union{DLNode{T}, Nothing}
DLNode(v) = new{typeof(v)}(v, nothing, nothing)
end
function insertpost(prevnode, node)
succ = prevnode.succ
prevnode.succ = node
node.pred = prevnode
node.succ = succ
if succ != nothing
succ.pred = node
end
return node
end
function delete(node)
succ = node.succ
pred = node.pred
succ != nothing && (succ.pred = pred)
pred != nothing && (pred.succ = succ)
return node
end
first(nd) = (while nd.pred != nothing nd = nd.prev end; nd)
last(nd) = (while nd.succ != nothing nd = nd.succ end; nd)
function atindex(nd, idx)
nd = first(nd)
while idx > 1 && nd != nothing
nd = nd.succ
idx -= 1
end
return nd
end
function printconnected(nd; fromtail = false)
if fromtail
nd = last(nd)
print(nd.value)
while nd.pred != nothing
nd = nd.pred
print(" -> $(nd.value)")
end
else
nd = first(nd)
print(nd.value)
while nd.succ != nothing
nd = nd.succ
print(" -> $(nd.value)")
end
end
println()
end
node1 = DLNode(1)
node2 = DLNode(2)
node3 = DLNode(3)
node4 = DLNode(4)
insertpost(node1, node2)
insertpost(node2, node3)
insertpost(node3, node4)
print("From beginning to end: "); printconnected(node1)
delete(atindex(node1, 3))
println("Deleting third node yields: "); printconnected(node1)
delete(node2)
println("Then deleting node2 yields: "); printconnected(node1)
</lang>{{out}}
<pre>
From beginning to end: 1 -> 2 -> 3 -> 4
Deleting third node yields:
1 -> 2 -> 4
Then deleting node2 yields:
1 -> 4
</pre>
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