src/bin/kth-largest-element-in-an-array.rs

Author: bestgopher

src/bin/kth-largest-element-in-an-array.rs

@@ -0,0 +1,42 @@
+fn main() {
+    Solution::find_kth_largest(vec![1], 1);
+}
+
+struct Solution;
+
+impl Solution {
+    pub fn find_kth_largest(nums: Vec<i32>, k: i32) -> i32 {
+        let mut nums = nums;
+        Self::heapify(&mut nums);
+
+        for i in 1..k as usize {
+            Self::heapify(&mut nums[i..])
+        }
+
+        nums[k as usize - 1]
+    }
+
+    fn heapify(nums: &mut [i32]) {
+        let mut index = (nums.len() - 1) / 2;
+
+        for i in (0..=index).rev() {
+            Self::down_heap(nums, i);
+        }
+    }
+
+    fn down_heap(nums: &mut [i32], mut index: usize) {
+        while index * 2 + 1 < nums.len() {
+            let mut max = index * 2 + 1;
+            if index * 2 + 2 < nums.len() && nums[index * 2 + 1] < nums[index * 2 + 2] {
+                max = index * 2 + 2;
+            }
+
+            if nums[max] > nums[index] {
+                nums.swap(max, index);
+                index = max;
+            } else {
+                break;
+            }
+        }
+    }
+}