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Day 15 - hashmap package needed to speed things up, but not in cran

Petra Lamborn 11 months ago
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      15.R

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15.R View File

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+library(hashmap)
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+
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+input <- as.integer(c(2,0,1,7,4,14,18))
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+
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+vals <- numeric(0)
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+sapply(1:2020, function(x) {
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+           if (x <= length(input)) {
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+               vals <<- c(vals, input[x])
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+               return(input[x])
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+           } else {
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+               can <- vals[x - 1]
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+               pos <- which(can == vals[1:(x - 2)])
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+               if (length(pos) == 0) {
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+                   vals <<- c(vals, 0)
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+                   return(0)
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+               } else {
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+                   le <- max(pos)
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+                   vals <<- c(vals, x - 1 - le)
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+                   return(x - 1 - le)
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+               }
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+           }
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+})
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+
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+
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+# Part 2
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+
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+hasha <- hashmap(as.integer(input[1:(length(input) - 1)]), as.integer(1:(length(input) - 1)))
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+# hashb <- hashmap(numeric(0), numeric(0))
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+
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+last <- tail(input, 1)
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+lb1 <- input[length(input) - 1]
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+
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+for (x in (length(input)):30000000) {
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+    if ((x %% 10000) == 0) {
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+        print(x)
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+    }
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+    hl <- hasha[[last]]
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+    lb1 <- last
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+    if (is.na(hl)) {
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+        last <- 0
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+    } else {
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+        last <- (x) - hl
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+    }
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+    hasha[[lb1]] <- x
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+    # print(lb1)
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+}
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+print(lb1)