feat(heap): add 703_kth_largest_element_in_a_stream.rs

Author: whisperpine

README.md

@@ -153,3 +153,9 @@ so that you can use `just tf TEST` command to test.
 | - | - | - |
 | 200. Number of Islands | Medium | [200_number_of_islands.rs](./tests/200_number_of_islands.rs) |
 | 695. Max Area of Island | Medium | [695_max_area_of_island.rs](./tests/695_max_area_of_island.rs) |
+
+### Heap / Priority Queue
+
+| Problem | Difficulty | Solution |
+| - | - | - |
+| 703. Kth Largest Element in a Stream | Easy | [703_kth_largest_element_in_a_stream.rs](./tests/703_kth_largest_element_in_a_stream.rs) |

tests/703_kth_largest_element_in_a_stream.rs

@@ -0,0 +1,54 @@
+// 703. Kth Largest Element in a Stream
+// https://leetcode.com/problems/kth-largest-element-in-a-stream/description/
+// Topics: Heap / Priority Queue.
+// Difficulty: Easy.
+
+#![allow(unused)]
+
+#[test]
+fn test_703_kth_largest_element_in_a_stream() {}
+
+#[derive(Debug)]
+pub struct Solution;
+
+// ---------------------------------
+// copy to leetcode starts from here
+// ---------------------------------
+
+use std::cmp::Reverse;
+use std::collections::BinaryHeap;
+
+struct KthLargest {
+    k: usize,
+    nums: BinaryHeap<Reverse<i32>>,
+}
+
+/**
+ * `&self` means the method takes an immutable reference.
+ * If you need a mutable reference, change it to `&mut self` instead.
+ */
+impl KthLargest {
+    fn new(k: i32, nums: Vec<i32>) -> Self {
+        let k = k as usize;
+        let mut heap = BinaryHeap::new();
+        for n in nums {
+            heap.push(Reverse(n));
+            if heap.len() > k {
+                heap.pop();
+            }
+        }
+        Self { k, nums: heap }
+    }
+
+    fn add(&mut self, val: i32) -> i32 {
+        self.nums.push(Reverse(val));
+        if self.nums.len() > self.k {
+            self.nums.pop();
+        }
+        self.nums.peek().unwrap().0
+    }
+}
+
+// Your KthLargest object will be instantiated and called as such:
+// let obj = KthLargest::new(k, nums);
+// let ret_1: i32 = obj.add(val);