day11

Author: plannapus

2024/day11.R

@@ -0,0 +1,67 @@
+input <- scan(read.input(11))
+options(digits=22)
+stones <- input
+#stones <- c(125,17)
+for(t in 1:25){
+  i <- 1
+  while(i<=length(stones)){
+    if(stones[i]==0){
+      stones[i] <- 1
+      i <- i+1
+    }else if(!nchar(stones[i])%%2){
+      n <- nchar(stones[i])/2
+      new <- as.integer(c(substr(stones[i],1,n),
+                          substr(stones[i],n+1,nchar(stones[i]))))
+      if(i==1){
+        stones <- c(new,stones[-i])
+      }else if(i==length(stones)){
+        stones <- c(stones[-i], new)
+      }else{
+        stones <- c(stones[1:(i-1)],new,stones[(i+1):length(stones)])
+      }
+      i <- i+2
+    }else{
+      stones[i] <- stones[i]*2024
+      i <- i+1
+    }
+  }
+  cat(t,":",length(stones),"\n")
+}
+length(stones)
+#185894
+
+blink <- \(x){
+  if(x==0){
+    return(1)
+  }else if(!nchar(x)%%2){
+    n <- nchar(x)/2
+    a <- as.integer(substr(x,1,n))
+    b <- as.integer(substr(x,n+1,nchar(x)))
+    return(c(a,b))
+  }else{
+    return(x*2024)
+  }
+}
+
+stones <- input
+memo <- cbind(stones,1)
+
+memorize <- \(x,n){
+  if(!x%in%memo2[,1]){
+    memo2 <<- rbind(memo2,c(x,n))
+  }else{
+    memo2[memo2[,1]==x,2] <<- memo2[memo2[,1]==x,2] + n
+  }
+}
+
+for(t in 1:75){
+  memo2 <- matrix(ncol=2,nrow=0)
+  for(i in memo[,1]){
+    for(j in blink(i)){
+      memorize(j,memo[memo[,1]==i,2])
+    }
+  }
+  memo <- memo2
+  cat(t,"\r")
+}
+#221632504974231

2024/screenshot.png

@@ -157,9 +157,9 @@ while(length(res)<8){
     res <- c(res,substr(md,6,6))
   }
   i <- i +1
-  cat(res,"\r")
+  if(!i%%10000)cat(res,"\r")
 }
-
+cat(res,sep="")
 
 # Day 6
 ## Part 1