problems(rs): add “2218. Maximum Value of K Coins From Piles”

Signed-off-by: Matej Focko <mfocko@redhat.com>

problems/maximum-value-of-k-coins-from-piles.rs

@@ -0,0 +1,73 @@
+use std::cmp;
+
+struct Solution {}
+impl Solution {
+    pub fn max_value_of_coins(piles: Vec<Vec<i32>>, k: i32) -> i32 {
+        let k = k as usize;
+
+        let mut mem: Vec<Vec<i32>> = vec![];
+        mem.resize_with(piles.len() + 1, || {
+            let mut v = vec![];
+            v.resize(k as usize + 1, 0);
+            v
+        });
+
+        for i in 1..=piles.len() {
+            for max_j in 0..=k {
+                let mut running_sum = 0;
+
+                for j in 0..=cmp::min(piles[i - 1].len(), max_j as usize) {
+                    if j > 0 {
+                        running_sum += piles[i - 1][j - 1];
+                    }
+                    mem[i][max_j] = cmp::max(mem[i][max_j], running_sum + mem[i - 1][max_j - j]);
+                }
+            }
+        }
+
+        mem[piles.len()][k]
+    }
+}
+
+fn main() {}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn example_1() {
+        let piles = vec![vec![1, 100, 3], vec![7, 8, 9]];
+        let expected = vec![0, 7, 101, 108, 116, 125, 128, 128];
+
+        for (k, right) in expected.iter().enumerate() {
+            assert_eq!(
+                Solution::max_value_of_coins(piles.clone(), k as i32),
+                *right
+            );
+        }
+    }
+
+    #[test]
+    fn example_2() {
+        let piles = vec![
+            vec![100],
+            vec![100],
+            vec![100],
+            vec![100],
+            vec![100],
+            vec![100],
+            vec![1, 1, 1, 1, 1, 1, 700],
+        ];
+        let expected = vec![
+            0, 100, 200, 300, 400, 500, 600, 706, 806, 906, 1006, 1106, 1206, 1306, 1306,
+        ];
+
+        for (k, right) in expected.iter().enumerate() {
+            assert_eq!(
+                Solution::max_value_of_coins(piles.clone(), k as i32),
+                *right
+            );
+        }
+    }
+}