Priority queue: Difference between revisions
Content added Content deleted
(R: return key and value) |
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keys <- values <- NULL |
keys <- values <- NULL |
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insert <- function(key, value) { |
insert <- function(key, value) { |
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ord <- findInterval(key, keys) |
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keys <<- append(keys, key, |
keys <<- append(keys, key, ord) |
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values <<- append(values, value, |
values <<- append(values, value, ord) |
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} |
} |
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pop <- function() { |
pop <- function() { |
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head <- values[[1]] |
head <- list(key=keys[1],value=values[[1]]) |
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values <<- values[-1] |
values <<- values[-1] |
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keys <<- keys[-1] |
keys <<- keys[-1] |
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| Line 3,567: | Line 3,567: | ||
pq$insert(2, "Tax return") |
pq$insert(2, "Tax return") |
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while(!pq$empty()) { |
while(!pq$empty()) { |
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with(pq$pop(), cat(key,":",value,"\n")) |
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}</lang>With output:<lang R> |
}</lang>With output:<lang R>1 : Solve RC tasks |
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2 : Tax return |
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3 : Clear drains |
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4 : Feed cat |
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5 : Make tea</lang>A similar implementation using R5 classes:<lang R>PriorityQueue <- |
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setRefClass("PriorityQueue", |
setRefClass("PriorityQueue", |
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fields = list(keys = "numeric", values = "list"), |
fields = list(keys = "numeric", values = "list"), |
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methods = list( |
methods = list( |
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insert = function(key,value) { |
insert = function(key,value) { |
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insert.order <- findInterval(key, keys) |
insert.order <- findInterval(key, keys) |
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keys <<- append(keys, key, insert.order) |
keys <<- append(keys, key, insert.order) |
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values <<- append(values, value, insert.order) |
values <<- append(values, value, insert.order) |
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}, |
}, |
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pop = function() { |
pop = function() { |
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head <- values[[1]] |
head <- list(key=keys[1],value=values[[1]]) |
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keys <<- keys[-1] |
keys <<- keys[-1] |
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values <<- values[-1] |
values <<- values[-1] |
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return(head) |
return(head) |
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}, |
}, |
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empty = function() length(keys) == 0 |
empty = function() length(keys) == 0 |
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))</lang>The only change in the example would be in the instantiation:<lang R>pq <- PriorityQueue$new()</lang> |
))</lang>The only change in the example would be in the instantiation:<lang R>pq <- PriorityQueue$new()</lang>. |
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=={{header|Racket}}== |
=={{header|Racket}}== |
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