diff --git a/2021/day4/src/bingo.rs b/2021/day4/src/bingo.rs
index 109015b..e66bba2 100644
--- a/2021/day4/src/bingo.rs
+++ b/2021/day4/src/bingo.rs
@@ -1,15 +1,17 @@
+type BingoNumber = ([usize; 2], u32, bool);
+
 #[derive(Debug, PartialEq)]
 pub struct BingoCard {
-    grid: Vec<([usize; 2], u32, bool)>,
+    grid: Vec<BingoNumber>,
 }
 
 impl BingoCard {
     pub fn from_input(input: &[&str]) -> Self {
-        let row_count = input.len();
+        let col_length = input.len();
 
         let grid = input
             .iter()
-            .zip(0..row_count)
+            .zip(0..col_length)
             .map(|(line, y)| {
                 let mut row_numbers = line
                     .replace("  ", " ")
@@ -25,10 +27,10 @@ impl BingoCard {
                     .zip(0..col_count)
                     .map(|(n, x)| ([x, y], *n, false))
                     // .into_iter()
-                    .collect::<Vec<([usize; 2], u32, bool)>>()
+                    .collect::<Vec<BingoNumber>>()
             })
             .flatten()
-            .collect::<Vec<([usize; 2], u32, bool)>>();
+            .collect::<Vec<BingoNumber>>();
 
         BingoCard { grid }
     }
@@ -67,6 +69,71 @@ fn mark_card(card: &mut BingoCard, bingo_num: &u32) {
     }
 }
 
+fn check_card(card: &BingoCard) -> Vec<&u32> {
+    let marked_cards = card
+        .grid
+        .iter()
+        .filter(|(_, _, mark)| *mark == true)
+        .collect::<Vec<&BingoNumber>>();
+
+    let col_length = card
+        .grid
+        .iter()
+        .filter(|([x, _], _, _)| *x == 0)
+        .map(|([_, y], _, _)| y)
+        .max()
+        .unwrap()
+        .clone()
+        + 1;
+
+    let row_length = card
+        .grid
+        .iter()
+        .filter(|([_, y], _, _)| *y == 0)
+        .map(|([x, _], _, _)| x)
+        .max()
+        .unwrap()
+        .clone()
+        + 1;
+
+    println!("col_length = {}", col_length);
+    println!("row_length = {}", row_length);
+
+    // (0..col_length).flat_map(|y| {
+    //         (0..row_length).flat_map(|x| {
+
+    // TODO: improve this to map over and return Vec of all winning to find ties!!
+
+    for y in 0..col_length {
+        let marked_in_col = marked_cards
+            .iter()
+            .filter(|([_, card_y], _, _)| *card_y == y)
+            .map(|([_, _], num, _)| num)
+            .collect::<Vec<&u32>>();
+
+        println!("{:?}", marked_in_col);
+
+        if marked_in_col.len() == col_length {
+            return marked_in_col;
+        }
+
+        for x in 0..row_length {
+            let marked_in_row = marked_cards
+                .iter()
+                .filter(|([card_x, _], _, _)| *card_x == x)
+                .map(|([_, _], num, _)| num)
+                .collect::<Vec<&u32>>();
+
+            if marked_in_row.len() == row_length {
+                return marked_in_row;
+            }
+        }
+    }
+    // .collect::<Vec<(bool, Vec<&u32>)>>()
+
+    return vec![];
+}
+
 #[cfg(test)]
 mod tests {
 
@@ -145,6 +212,74 @@ mod tests {
         assert_eq!(actual_card, expected_marked_card_4);
     }
 
+    #[test]
+    fn check_card_example_row_losing() {
+        #[rustfmt::skip]
+        let losing_card = BingoCard { grid: vec![
+            ([0,0], 22, false),([1,0], 13, false),([2,0], 17, false),([3,0], 11, false),([4,0], 0, false),
+            ([0,1], 8, false),([1,1], 2, false),([2,1], 23, false),([3,1], 4, false),([4,1], 24, false),
+            ([0,2], 21, true),([1,2], 9, true),([2,2], 14, true),([3,2], 16, false),([4,2], 7, false),
+            ([0,3], 6, false),([1,3], 10, false),([2,3], 3, false),([3,3], 18, false),([4,3], 5, false),
+            ([0,4], 1, false),([1,4], 12, false),([2,4], 20, false),([3,4], 15, false),([4,4], 19, false),
+        ]};
+
+        let actual_result = check_card(&losing_card);
+        let expected_result: Vec<&u32> = vec![];
+
+        assert_eq!(actual_result, expected_result);
+    }
+
+    #[test]
+    fn check_card_example_row_winning() {
+        #[rustfmt::skip]
+        let losing_card = BingoCard { grid: vec![
+            ([0,0], 22, false),([1,0], 13, false),([2,0], 17, false),([3,0], 11, false),([4,0], 0, false),
+            ([0,1], 8, false),([1,1], 2, false),([2,1], 23, false),([3,1], 4, false),([4,1], 24, false),
+            ([0,2], 21, true),([1,2], 9, true),([2,2], 14, true),([3,2], 16, true),([4,2], 7, true),
+            ([0,3], 6, false),([1,3], 10, false),([2,3], 3, false),([3,3], 18, false),([4,3], 5, false),
+            ([0,4], 1, false),([1,4], 12, false),([2,4], 20, false),([3,4], 15, false),([4,4], 19, false),
+        ]};
+
+        let actual_result = check_card(&losing_card);
+        let expected_result: Vec<&u32> = vec![&21, &9, &14, &16, &7];
+
+        assert_eq!(actual_result, expected_result);
+    }
+
+    #[test]
+    fn check_card_example_col_losing() {
+        #[rustfmt::skip]
+        let losing_card = BingoCard { grid: vec![
+            ([0,0], 22, true),([1,0], 13, false),([2,0], 17, false),([3,0], 11, false),([4,0], 0, false),
+            ([0,1], 8, true),([1,1], 2, false),([2,1], 23, false),([3,1], 4, false),([4,1], 24, false),
+            ([0,2], 21, true),([1,2], 9, false),([2,2], 14, false),([3,2], 16, false),([4,2], 7, false),
+            ([0,3], 6, false),([1,3], 10, false),([2,3], 3, false),([3,3], 18, false),([4,3], 5, false),
+            ([0,4], 1, false),([1,4], 12, false),([2,4], 20, false),([3,4], 15, false),([4,4], 19, false),
+        ]};
+
+        let actual_result = check_card(&losing_card);
+        let expected_result: Vec<&u32> = vec![];
+
+        assert_eq!(actual_result, expected_result);
+    }
+
+    #[test]
+    fn check_card_example_col_winning() {
+        #[rustfmt::skip]
+        let losing_card = BingoCard { grid: vec![
+            ([0,0], 22, true),([1,0], 13, false),([2,0], 17, false),([3,0], 11, false),([4,0], 0, false),
+            ([0,1], 8, true),([1,1], 2, false),([2,1], 23, false),([3,1], 4, false),([4,1], 24, false),
+            ([0,2], 21, true),([1,2], 9, false),([2,2], 14, false),([3,2], 16, false),([4,2], 7, false),
+            ([0,3], 6, true),([1,3], 10, false),([2,3], 3, false),([3,3], 18, false),([4,3], 5, false),
+            ([0,4], 1, true),([1,4], 12, false),([2,4], 20, false),([3,4], 15, false),([4,4], 19, false),
+        ]};
+
+        let actual_result = check_card(&losing_card);
+        let expected_result: Vec<&u32> = vec![&22, &8, &21, &6, &1];
+
+        assert_eq!(actual_result, expected_result);
+    }
+
     #[test]
     fn construct_empty_bingo_card_from_input() {
         let input = vec![];