Merge pull request neetcode-gh#3384 from unw9527/main

Update 0215-kth-largest-element-in-an-array.cpp

cpp/0215-kth-largest-element-in-an-array.cpp

@@ -69,27 +69,44 @@ class Solution {
 */
 
 // Video's QuickSelect implementation
+// class Solution {
+// public:
+// int findKthLargest(vector<int>& nums, int k) {
+// int index = nums.size() - k;
+// return quickSelect(nums, index, 0, nums.size() - 1);
+// }
+// private:
+// int quickSelect(vector<int>& nums, int k, int l, int r){
+// int pivot = nums[r];
+// int p_pos = l;
+// for (int i = l; i < r; ++i){
+// if (nums[i] <= pivot){
+// swap(nums[i], nums[p_pos]);
+// ++p_pos;
+// }
+// }
+// swap(nums[p_pos], nums[r]);
+// if (k < p_pos)
+// return quickSelect(nums, k, l, p_pos - 1);
+// if (k > p_pos)
+// return quickSelect(nums, k, p_pos + 1, r);
+// return nums[p_pos];
+// }
+// };
+
+// Solution that can pass current tests
 class Solution {
 public:
  int findKthLargest(vector<int>& nums, int k) {
- int index = nums.size() - k;
- return quickSelect(nums, index, 0, nums.size() - 1);
- }
-private:
- int quickSelect(vector<int>& nums, int k, int l, int r){
- int pivot = nums[r];
- int p_pos = l;
- for (int i = l; i < r; ++i){
- if (nums[i] <= pivot){
- swap(nums[i], nums[p_pos]);
- ++p_pos;
- }
+ int pivot = nums[rand() % nums.size()];
+ vector<int> left, mid, right;
+ for (auto num: nums) {
+ if (num > pivot) left.push_back(num);
+ else if (num == pivot) mid.push_back(num);
+ else right.push_back(num);
  }
- swap(nums[p_pos], nums[r]);
- if (k < p_pos)
- return quickSelect(nums, k, l, p_pos - 1);
- if (k > p_pos)
- return quickSelect(nums, k, p_pos + 1, r);
- return nums[p_pos];
+ if (k <= left.size()) return findKthLargest(left, k);
+ else if (k <= left.size() + mid.size()) return mid[0];
+ else return findKthLargest(right, k - left.size() - mid.size());
  }
 };