From 6a58f37ad7ab94bda1357b3faf1ebf83dd375d00 Mon Sep 17 00:00:00 2001
From: fuckwit <me@fucktwit.dev>
Date: Thu, 16 Nov 2023 23:12:26 +0100
Subject: [PATCH] add combinations iterator. it has bugs

---
 input/year2016/day03.txt |  2 +-
 src/util/index.rs        | 19 ++++--------
 src/util/iter.rs         | 64 ++++++++++++++++++++++++++++++++++------
 src/year2016/day03.rs    |  4 +--
 4 files changed, 64 insertions(+), 25 deletions(-)

diff --git a/input/year2016/day03.txt b/input/year2016/day03.txt
index 68a1bab..40378d0 100644
--- a/input/year2016/day03.txt
+++ b/input/year2016/day03.txt
@@ -1596,4 +1596,4 @@
   188  509  421
   850  394  702
    68  744  665
-  919  923  873
+  919  923  873
\ No newline at end of file
diff --git a/src/util/index.rs b/src/util/index.rs
index 736f18f..377fe7d 100644
--- a/src/util/index.rs
+++ b/src/util/index.rs
@@ -9,12 +9,14 @@ macro_rules! impl_ix {
             pub type $t = Dim<[Ix; $n]>;
 
             impl From<[Ix; $n]> for $t {
+                #[inline]
                 fn from(value: [Ix; $n]) -> Self {
                     Dim(value)
                 }
             }
 
             #[allow(non_snake_case)]
+            #[inline]
             pub fn $t() -> Dim<[Ix; $n]> { Dim([0; $n]) }
         )+
     };
@@ -42,16 +44,6 @@ impl Ix2 {
         self.0[1]
     }
 
-    pub fn within(&self, lower: impl Into<Ix2>, upper: impl Into<Ix2>) -> bool {
-        let lower = lower.into();
-        let upper = upper.into();
-
-        self.x() >= lower.x()
-            && self.x() <= upper.x()
-            && self.y() >= lower.y()
-            && self.y() <= upper.y()
-    }
-
     #[inline]
     pub fn clockwise(self) -> Self {
         Dim([-self.y(), self.x()])
@@ -61,11 +53,12 @@ impl Ix2 {
     pub fn counter_clockwise(self) -> Self {
         Dim([self.y(), -self.x()])
     }
-
+    
+    #[inline]
     pub fn manhatten(&self, other: Ix2) -> i64 {
-        (self.0[0] - other.0[0]).abs() + (self.0[1] - other.0[1]).abs()
+        (self.x() - other.x()).abs() + (self.y() - other.y()).abs()
     }
-
+    
     pub fn linearize(&self, width: usize, height: usize) -> usize {
         self.y() as usize * height + (width - 1)
     }
diff --git a/src/util/iter.rs b/src/util/iter.rs
index 8706af2..99fa977 100644
--- a/src/util/iter.rs
+++ b/src/util/iter.rs
@@ -1,27 +1,73 @@
-pub struct Combinations<I: Iterator> {
+pub struct Combinations<I, T>
+where
+    I: Iterator<Item = T>,
+{
     indices: Vec<usize>,
+    k: usize,
     size: usize,
     pool: Vec<I::Item>,
-    first: bool,
 }
 
-impl<I: Iterator> Combinations<I> {
-    pub fn new(iter: I, comb: usize) -> Self {
+impl<I, T> Combinations<I, T>
+where
+    I: Iterator<Item = T>,
+{
+    pub fn new(iter: I, k: usize) -> Self {
         let pool: Vec<I::Item> = iter.collect();
 
         Self {
-            indices: Vec::with_capacity(comb),
+            indices: (0..k).collect(),
+            k,
             size: pool.len(),
             pool,
-            first: true,
         }
     }
 }
 
-impl<I: Iterator> Iterator for Combinations<I> {
-    type Item = I::Item;
+impl<I, T> Iterator for Combinations<I, T>
+where
+    I: Iterator<Item = T>,
+    T: Copy,
+{
+    type Item = Vec<T>;
 
     fn next(&mut self) -> Option<Self::Item> {
-        todo!()
+        let mut out = Vec::with_capacity(self.size);
+        let mut indices = Vec::with_capacity(self.k);
+        let mut incremented = false;
+
+        for i in &self.indices {
+            out.push(self.pool[*i]);
+        }
+
+        self.indices.reverse();
+        let mut iter = self.indices.iter().enumerate();
+        while let Some((count, idx)) = iter.next() {
+            if incremented || *idx == self.size - (count + 1) {
+                indices.push(*idx);
+                continue;
+            }
+            indices.push(idx + 1);
+            incremented = true;
+        }
+        if !incremented {
+            return None;
+        }
+        indices.reverse();
+        self.indices = indices;
+        Some(out)
     }
 }
+
+pub trait CombinationsIterator<T>: Iterator<Item = T> + Sized {
+    fn combinations(self, k: usize) -> Combinations<Self, T> {
+        Combinations::new(self, k)
+    }
+}
+
+impl<I, T> CombinationsIterator<T> for I where I: Iterator<Item = T> {}
+
+#[test]
+fn test_iter() {
+    println!("{:?}", [1, 2, 3].iter().combinations(2).collect::<Vec<_>>());
+}
diff --git a/src/year2016/day03.rs b/src/year2016/day03.rs
index 4551605..6cb45dc 100644
--- a/src/year2016/day03.rs
+++ b/src/year2016/day03.rs
@@ -1,7 +1,7 @@
 use crate::util::parse::ParseExt;
 
 pub fn part1(input: &str) -> impl std::fmt::Display {
-    let vec: Vec<Vec<u32>> = input.lines().map(|s| s.u32s().collect()).combin;
+    //let vec: Vec<Vec<u32>> = input.lines().map(|s| s.u32s().collect());
 
     ""
 }
@@ -17,5 +17,5 @@ fn test_part1() {
 
 #[test]
 fn test_part2() {
-    assert_eq!("", part2("").to_string())
+    assert_eq!("", part2("").to_string());
 }