day5

Not super happy with this, fell back to iterative programming pretty heavily (:
Also a ton of .unwrap(), but this is an artifical problem not a real world

1 files changed, 65 insertions, 0 deletions

diff --git a/src/day5.rs b/src/day5.rs
new file mode 100644
index 0000000..806ddf2
--- /dev/null
+++ b/src/day5.rs
@@ -0,0 +1,65 @@
+use std::{collections::HashMap};
+use regex::Regex;
+
+pub fn run(input: String) {
+    let lines: Vec<&str> = input.lines().collect();
+    let mut lix: usize = 0;
+    let mut ship: HashMap<usize, Vec<char>> = HashMap::new();
+    for line in lines.iter() {
+        lix += 1;
+        let chrs: Vec<char> = line.chars().collect();
+        // Line with just container numbers after the containers themselves
+        if chrs[1] == '1' {
+            break;
+        }
+        for (ix, container) in chrs.chunks(4).enumerate() {
+            let stack = ship.entry(ix+1).or_insert(Vec::new());// key starts at 1, of course
+            let payload = container[1];
+            if payload.is_alphabetic() {
+                stack.insert(0, payload) // last one we found is always the bottom of the stack
+            }
+        }
+    }
+    println!("ship: {:?}", ship);
+    lix += 1;
+
+
+    let re = Regex::new(r"^move (\d+) from (\d+) to (\d+)$").unwrap();
+    assert!(re.is_match("move 1 from 2 to 4"));
+    for line in lines[lix..].iter() {
+        // parse the instruction... 
+        // "move 1 from 2 to 1"
+
+        let mm = re.captures(line).expect("instruction didn't match regex???");
+        let n: usize = mm.get(1).unwrap().as_str().parse().unwrap();
+        let ifrom: usize = mm.get(2).unwrap().as_str().parse().unwrap();
+        let ito: usize = mm.get(3).unwrap().as_str().parse().unwrap();
+        println!("moving {} from {} to {}", n, ifrom, ito);
+        // for _ in 0..n {
+        //     let stackfrom = ship.get_mut(&ifrom).expect("couldn't find stack to pop from!");
+        //     let ch = stackfrom.pop().expect("failed to pop from stack! maybe it was empty?");
+        //     let stackto = ship.get_mut(&ito).expect("couldn't find stack to push to!");
+        //     stackto.push(ch);
+        // }
+        let stackfrom = ship.get_mut(&ifrom).expect("couldn't find stack to pop from!");
+        let mut chunk: Vec<char> = Vec::new();
+        for _ in 0..n {
+            let ch = stackfrom.pop().expect("failed to pop from stack! maybe it was empty?");
+            chunk.push(ch);
+        }
+        let stackto = ship.get_mut(&ito).expect("couldn't find stack to push to!");
+        for _ in 0..n {
+            let ch = chunk.pop().unwrap();
+            stackto.push(ch);
+        }
+    }
+
+    print!("day 5: ");
+    for i in 1..(ship.keys().len()+1) {
+        let topch = ship.get(&i).unwrap().last().unwrap();
+        print!("{}", topch);
+    }
+    print!("\n");
+    
+
+}
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