day 7 pt1

data/examples/07.txt

@@ -0,0 +1,9 @@
+190: 10 19
+3267: 81 40 27
+83: 17 5
+156: 15 6
+7290: 6 8 6 15
+161011: 16 10 13
+192: 17 8 14
+21037: 9 7 18 13
+292: 11 6 16 20

src/bin/07.rs

@@ -0,0 +1,76 @@
+advent_of_code::solution!(7);
+
+pub fn part_one(input: &str) -> Option<usize> {
+    let total: usize = input.lines().filter_map(|line| {
+        // println!("{line}");
+        let m: Vec<&str> = line.split(": ").collect();
+        let total = m[0].parse::<usize>().unwrap();
+        let values: Vec<usize> = m[1].split(' ').map(|v| v.parse::<usize>().unwrap()).collect();
+
+        // println!("LINE: {} = {:?}", total, values);
+
+        if can_calc(total, values) { Some(total) } else { None }
+        // Some(total)
+    }).sum();
+    // println!("TOTAL: {}", total);
+
+    return Some(total);
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    None
+}
+
+// allowed operators: + and *
+// all possible options OP^(values count - 1)
+// eg 190: 10 19 -- has TWO possible paths, 10 + 19 and 10 * 19
+// eg 123: 4 5 6 3 -- has 8 possible paths; 4+5+6+3,  4+5+6*3, ... 4*5*6*3
+
+fn can_calc(total: usize, values: Vec<usize>) -> bool {
+    let is_valid = values.into_iter().fold(vec![0 as usize], |subtotals, next_value| {
+        process(&subtotals, next_value)
+    }).iter().any(|t| *t == total);
+
+    is_valid
+}
+
+fn process(sum: &Vec<usize>, next_value: usize) -> Vec<usize> {
+    sum.into_iter().flat_map(|v| {
+        vec![v + next_value, v * next_value]
+    }).collect()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_process() {
+        let sum: Vec<u32> = vec![1];
+        let next_value = 10;
+
+        let result = process(&sum, next_value);
+        assert_eq!(result, vec![11, 10]);
+    }
+
+    #[test]
+    fn test_can_calc() {
+        let values: Vec<u32> = vec![1,2,3,4];
+        let total: u32 = 10;
+
+        let result = can_calc(total, values);
+        assert_eq!(result, true);
+    }
+
+    #[test]
+    fn test_part_one() {
+        let result = part_one(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(3749));
+    }
+
+    #[test]
+    fn test_part_two() {
+        let result = part_two(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, None);
+    }
+}