20240309 Finished

src/problem/mod.rs

@@ -68,3 +68,4 @@ mod p1976_number_of_ways_to_arrive_at_destination;
 mod p2917_find_the_k_or_of_an_array;
 mod p2575_find_the_divisibility_array_of_a_string;
 mod p2834_find_the_minimum_possible_sum_of_a_beautiful_array;
+mod p2386_find_the_k_sum_of_an_array;

src/problem/p2386_find_the_k_sum_of_an_array.rs

@@ -0,0 +1,84 @@
+/**
+ * [2386] Find the K-Sum of an Array
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::BinaryHeap;
+
+#[derive(PartialEq, Eq)]
+struct Node {
+    sum: i64,
+    last: usize,
+}
+
+impl PartialOrd for Node {
+    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+        other.sum.partial_cmp(&self.sum)
+    }
+}
+
+impl Ord for Node {
+    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+        other.sum.cmp(&self.sum)
+    }
+}
+
+impl Solution {
+    pub fn k_sum(nums: Vec<i32>, k: i32) -> i64 {
+        let mut total = 0;
+        let mut nums: Vec<i64> = nums
+            .iter()
+            .map(|x| {
+                if *x > 0 {
+                    let x = *x as i64;
+                    total += x;
+                    x
+                } else {
+                    -x as i64
+                }
+            })
+            .collect();
+
+        nums.sort_unstable();
+
+        let mut heap = BinaryHeap::new();
+        heap.push(Node {
+            sum: nums[0],
+            last: 0,
+        });
+
+        let mut result = 0;
+        for _ in 1..k {
+            let top = heap.pop().unwrap();
+
+            result = top.sum;
+            if top.last == nums.len() - 1 {
+                continue;
+            }
+
+            heap.push(Node {
+                sum: top.sum + nums[top.last + 1],
+                last: top.last + 1,
+            });
+            heap.push(Node {
+                sum: top.sum - nums[top.last] + nums[top.last + 1],
+                last: top.last + 1,
+            });
+        }
+
+        total - result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2386() {
+        assert_eq!(2, Solution::k_sum(vec![2, 4, -2], 5));
+    }
+}