Add problem 2280: Minimum Lines to Represent a Line Chart

src/lib.rs

@@ -1691,6 +1691,7 @@ pub mod problem_2274_maximum_consecutive_floors_without_special_floors;
 pub mod problem_2275_largest_combination_with_bitwise_and_greater_than_zero;
 pub mod problem_2278_percentage_of_letter_in_string;
 pub mod problem_2279_maximum_bags_with_full_capacity_of_rocks;
+pub mod problem_2280_minimum_lines_to_represent_a_line_chart;
 
 #[cfg(test)]
 mod test_utilities;

src/problem_2280_minimum_lines_to_represent_a_line_chart/dfs.rs

@@ -0,0 +1,49 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl Solution {
+    pub fn minimum_lines(stock_prices: Vec<Vec<i32>>) -> i32 {
+        let mut stock_prices = stock_prices
+            .into_iter()
+            .map(|prices| Box::<[_; 2]>::try_from(prices.into_boxed_slice()).unwrap())
+            .collect::<Vec<_>>();
+
+        stock_prices.sort_unstable_by_key(|prices| prices[0] as u32);
+
+        let mut prev_day = 0;
+        let mut prev_price = i32::MAX;
+        let mut prev_ratio = (1, 0);
+        let mut result = -1;
+
+        for stock_price in stock_prices {
+            let [day, price] = *stock_price;
+            let ratio = (price - prev_price, day - prev_day);
+
+            result +=
+                i32::from(i64::from(prev_ratio.0) * i64::from(ratio.1) != i64::from(prev_ratio.1) * i64::from(ratio.0));
+
+            prev_day = day;
+            prev_price = price;
+            prev_ratio = ratio;
+        }
+
+        result
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn minimum_lines(stock_prices: Vec<Vec<i32>>) -> i32 {
+        Self::minimum_lines(stock_prices)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}

src/problem_2280_minimum_lines_to_represent_a_line_chart/mod.rs

@@ -0,0 +1,39 @@
+pub mod dfs;
+
+pub trait Solution {
+    fn minimum_lines(stock_prices: Vec<Vec<i32>>) -> i32;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [
+            (
+                &[[1, 7], [2, 6], [3, 5], [4, 4], [5, 4], [6, 3], [7, 2], [8, 1]] as &[_],
+                3,
+            ),
+            (&[[3, 4], [1, 2], [7, 8], [2, 3]], 1),
+            (
+                &[
+                    [1, 1],
+                    [2, 2],
+                    [3, 3],
+                    [4, 5],
+                    [5, 7],
+                    [6, 6],
+                    [7, 5],
+                    [8, 4],
+                    [9, 4],
+                    [10, 4],
+                ],
+                4,
+            ),
+        ];
+
+        for (stock_prices, expected) in test_cases {
+            assert_eq!(S::minimum_lines(stock_prices.iter().map(Vec::from).collect()), expected);
+        }
+    }
+}