Dijkstra's Algorithm pseudocode “U” symbol
I'm currently trying to follow pseudocode for Dijkstra's Algorithm, but I'm having difficulty understand what one of the lines means.
DijkstrasAlgorithm(G, w, s)
InitalizeSingleSource(G, s)
S = 0
Q = G.V
while Q != 0
u = ExtractMin(Q)
S = S∪{u}
for each vertex v ∈ G.Adj[u]
Relax(u, v, w)
This part right here "S = S∪{u}" is what's confusing me. I'm not sure what S is supposed to be equal to. Could someone explain? Thanks!
pseudocode dijkstra
edited Nov 27 '18 at 20:52
Neil Butterworth
27.2k54681
asked Nov 27 '18 at 20:50
DamerianDamerian
294
add a comment |
I'm currently trying to follow pseudocode for Dijkstra's Algorithm, but I'm having difficulty understand what one of the lines means.
DijkstrasAlgorithm(G, w, s)
InitalizeSingleSource(G, s)
S = 0
Q = G.V
while Q != 0
u = ExtractMin(Q)
S = S∪{u}
for each vertex v ∈ G.Adj[u]
Relax(u, v, w)
This part right here "S = S∪{u}" is what's confusing me. I'm not sure what S is supposed to be equal to. Could someone explain? Thanks!
pseudocode dijkstra
edited Nov 27 '18 at 20:52
Neil Butterworth
27.2k54681
asked Nov 27 '18 at 20:50
DamerianDamerian
294
Thats a union operator from set theory
– Minn
Nov 27 '18 at 20:53
add a comment |
I'm currently trying to follow pseudocode for Dijkstra's Algorithm, but I'm having difficulty understand what one of the lines means.
DijkstrasAlgorithm(G, w, s)
InitalizeSingleSource(G, s)
S = 0
Q = G.V
while Q != 0
u = ExtractMin(Q)
S = S∪{u}
for each vertex v ∈ G.Adj[u]
Relax(u, v, w)
This part right here "S = S∪{u}" is what's confusing me. I'm not sure what S is supposed to be equal to. Could someone explain? Thanks!
pseudocode dijkstra
edited Nov 27 '18 at 20:52
Neil Butterworth
27.2k54681
asked Nov 27 '18 at 20:50
DamerianDamerian
294
I'm currently trying to follow pseudocode for Dijkstra's Algorithm, but I'm having difficulty understand what one of the lines means.
DijkstrasAlgorithm(G, w, s)
InitalizeSingleSource(G, s)
S = 0
Q = G.V
while Q != 0
u = ExtractMin(Q)
S = S∪{u}
for each vertex v ∈ G.Adj[u]
Relax(u, v, w)
This part right here "S = S∪{u}" is what's confusing me. I'm not sure what S is supposed to be equal to. Could someone explain? Thanks!
pseudocode dijkstra
pseudocode dijkstra
edited Nov 27 '18 at 20:52
Neil Butterworth
27.2k54681
asked Nov 27 '18 at 20:50
DamerianDamerian
294
edited Nov 27 '18 at 20:52
Neil Butterworth
27.2k54681
asked Nov 27 '18 at 20:50
DamerianDamerian
294
edited Nov 27 '18 at 20:52
Neil Butterworth
27.2k54681
edited Nov 27 '18 at 20:52
Neil Butterworth
27.2k54681
edited Nov 27 '18 at 20:52
Neil Butterworth
27.2k54681
27.2k54681
asked Nov 27 '18 at 20:50
DamerianDamerian
294
asked Nov 27 '18 at 20:50
DamerianDamerian
294
asked Nov 27 '18 at 20:50
DamerianDamerian
294
294
Thats a union operator from set theory
– Minn
Nov 27 '18 at 20:53
add a comment |
Thats a union operator from set theory
– Minn
Nov 27 '18 at 20:53
Thats a union operator from set theory
– Minn
Nov 27 '18 at 20:53
Thats a union operator from set theory
– Minn
Nov 27 '18 at 20:53
add a comment |
1 Answer
1
active
oldest
votes
That’s the set union operator. S here is the set of all nodes for which the shortest path has been computed, and this line means “add the node u to that set.”
Mechanically, S ∪ {u} is the set consisting of everything already in S, plus the node u. That’s why S = S ∪ {u} means to add u to S.
(As a note, I think the pseudocode has a typo in where S was declared. You probably meant to initialize it to the empty set ∅ rather than the number 0.)
Dijkstra’s algorithm is a pretty tough one to understand purely from pseudocode. I recommend checking out a tutorial somewhere so that you have a high-level intuition for what’s going on. It’s much easier to understand this pseudocode by mapping the contents onto your conceptual understanding.
answered Nov 27 '18 at 20:53
templatetypedeftemplatetypedef
266k69675896
add a comment |
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1 Answer
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active
oldest
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1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
That’s the set union operator. S here is the set of all nodes for which the shortest path has been computed, and this line means “add the node u to that set.”
Mechanically, S ∪ {u} is the set consisting of everything already in S, plus the node u. That’s why S = S ∪ {u} means to add u to S.
(As a note, I think the pseudocode has a typo in where S was declared. You probably meant to initialize it to the empty set ∅ rather than the number 0.)
Dijkstra’s algorithm is a pretty tough one to understand purely from pseudocode. I recommend checking out a tutorial somewhere so that you have a high-level intuition for what’s going on. It’s much easier to understand this pseudocode by mapping the contents onto your conceptual understanding.
answered Nov 27 '18 at 20:53
templatetypedeftemplatetypedef
266k69675896
add a comment |
That’s the set union operator. S here is the set of all nodes for which the shortest path has been computed, and this line means “add the node u to that set.”
Mechanically, S ∪ {u} is the set consisting of everything already in S, plus the node u. That’s why S = S ∪ {u} means to add u to S.
(As a note, I think the pseudocode has a typo in where S was declared. You probably meant to initialize it to the empty set ∅ rather than the number 0.)
Dijkstra’s algorithm is a pretty tough one to understand purely from pseudocode. I recommend checking out a tutorial somewhere so that you have a high-level intuition for what’s going on. It’s much easier to understand this pseudocode by mapping the contents onto your conceptual understanding.
answered Nov 27 '18 at 20:53
templatetypedeftemplatetypedef
266k69675896
add a comment |
That’s the set union operator. S here is the set of all nodes for which the shortest path has been computed, and this line means “add the node u to that set.”
Mechanically, S ∪ {u} is the set consisting of everything already in S, plus the node u. That’s why S = S ∪ {u} means to add u to S.
(As a note, I think the pseudocode has a typo in where S was declared. You probably meant to initialize it to the empty set ∅ rather than the number 0.)
Dijkstra’s algorithm is a pretty tough one to understand purely from pseudocode. I recommend checking out a tutorial somewhere so that you have a high-level intuition for what’s going on. It’s much easier to understand this pseudocode by mapping the contents onto your conceptual understanding.
answered Nov 27 '18 at 20:53
templatetypedeftemplatetypedef
266k69675896
That’s the set union operator. S here is the set of all nodes for which the shortest path has been computed, and this line means “add the node u to that set.”
Mechanically, S ∪ {u} is the set consisting of everything already in S, plus the node u. That’s why S = S ∪ {u} means to add u to S.
(As a note, I think the pseudocode has a typo in where S was declared. You probably meant to initialize it to the empty set ∅ rather than the number 0.)
Dijkstra’s algorithm is a pretty tough one to understand purely from pseudocode. I recommend checking out a tutorial somewhere so that you have a high-level intuition for what’s going on. It’s much easier to understand this pseudocode by mapping the contents onto your conceptual understanding.
answered Nov 27 '18 at 20:53
templatetypedeftemplatetypedef
266k69675896
answered Nov 27 '18 at 20:53
templatetypedeftemplatetypedef
266k69675896
answered Nov 27 '18 at 20:53
templatetypedeftemplatetypedef
266k69675896
answered Nov 27 '18 at 20:53
templatetypedeftemplatetypedef
266k69675896
266k69675896
add a comment |
add a comment |
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Thats a union operator from set theory
– Minn
Nov 27 '18 at 20:53