It works ! \o/

src/prob5.rs

@@ -1,9 +1,11 @@
+use std::collections::VecDeque;
+
 use nom::{
     branch::alt,
     bytes::complete::{tag, take, take_while1},
     combinator::{all_consuming, map, map_res, opt},
-    sequence::{delimited, preceded, tuple},
-    Finish, IResult,
+    Finish,
+    IResult, sequence::{delimited, preceded, tuple},
 };
 
 #[derive(Debug)]
@@ -53,16 +55,22 @@ fn parse_crate_line(i: &str) -> IResult<&str, Vec<Option<char>>> {
     Ok((i, v))
 }
 
-fn transpose_rev<T>(v: Vec<Vec<Option<T>>>) -> Vec<Vec<T>> {
+fn transpose_rev<T>(v: Vec<Vec<Option<T>>>) -> Vec<VecDeque<T>> {
     assert!(!v.is_empty());
-    let len = v[0].len();
+    let len = v
+        .iter()
+        .max_by(|x, y| x.len().cmp(&y.len()))
+        .unwrap_or_else(|| panic!(""))
+        .len();
+    println!("{len}, {}", v[0].len());
     let mut iters: Vec<_> = v.into_iter().map(|n| n.into_iter()).collect();
     (0..len)
         .map(|_| {
             iters
                 .iter_mut()
-                .filter_map(|n| n.next().unwrap())
-                .collect::<Vec<T>>()
+                .filter_map(|n| n.next())
+                .flatten()
+                .collect::<VecDeque<T>>()
         })
         .collect()
 }
@@ -88,7 +96,7 @@ fn parse_instruction(i: &str) -> IResult<&str, Instruction> {
     )(i)
 }
 
-fn parser(content: &str) {
+fn parser(content: &str) -> String {
     let mut lines = content.lines();
     let crate_lines = (&mut lines)
         .map_while(|line| {
@@ -99,22 +107,36 @@ fn parser(content: &str) {
         })
         .collect();
 
-    let crate_columns = transpose_rev(crate_lines);
-
-    crate_columns.iter().for_each(|item| println!("{item:?}"));
+    let mut crate_columns = transpose_rev(crate_lines);
 
     assert!(lines.next().unwrap().is_empty());
 
-    let instructions: Vec<_> = lines
+    lines
         .map(|line| all_consuming(parse_instruction)(line).finish().unwrap().1)
-        .collect();
-    for ins in &instructions {
-        println!("{ins:?}");
-    }
+        .into_iter()
+        .for_each(|ins| {
+            (0..ins.quantity).for_each(|_| {
+                let tmp = crate_columns
+                    .get_mut(ins.src)
+                    .unwrap_or_else(|| {
+                        panic!("Index {} is out of bound of crate_columns.", ins.src)
+                    })
+                    .pop_front()
+                    .unwrap_or_else(|| panic!("Could not pop front the column {}", ins.src));
+                crate_columns
+                    .get_mut(ins.dst)
+                    .unwrap_or_else(|| panic!("Index {} is out of bound", ins.dst))
+                    .push_front(tmp);
+            });
+        });
+    let mut answer = String::new();
+    crate_columns
+        .iter()
+        .for_each(|item| answer.push(*item.front().unwrap_or_else(|| panic!(""))));
+    answer
 }
 
-pub fn solve(file_path: &str) -> i32 {
+pub fn solve(file_path: &str) -> String {
     let content = std::fs::read_to_string(file_path).unwrap_or_else(|err| panic!("{err}"));
-    parser(&content);
-    0
+    parser(&content)
 }