k largest elements

Author: sachuverma

DSA Crack Sheet/README.md

@@ -284,6 +284,8 @@
 
 - [Building Heap from Array](https://www.geeksforgeeks.org/building-heap-from-array/ "view post")
 - [Heap Sort](https://practice.geeksforgeeks.org/problems/heap-sort/1# "view question") - [Cpp Solution](./solutions/Heap%20Sort.cpp)
+- [Maximum of all subarrays of size k](https://practice.geeksforgeeks.org/problems/maximum-of-all-subarrays-of-size-k3101/1# "view question") - [Cpp Solution](./solutions/Maximum%20of%20all%20subarrays%20of%20size%20k.cpp)
+- [k largest elements](https://practice.geeksforgeeks.org/problems/k-largest-elements4206/1# "view question") - [Cpp Solution](./solutions/k%20largest%20elements.cpp)
 - []( "view question") - [Cpp Solution](./solutions/.cpp)
 
 ### Graphs

DSA Crack Sheet/solutions/k largest elements.cpp

@@ -0,0 +1,48 @@
+/*
+k largest elements
+==================
+
+Given an array Arr of N positive integers, find K largest elements from the array.  The output elements should be printed in decreasing order.
+
+Example 1:
+Input:
+N = 5, K = 2
+Arr[] = {12, 5, 787, 1, 23}
+Output: 787 23
+Explanation: 1st largest element in the
+array is 787 and second largest is 23.
+
+Example 2:
+Input:
+N = 7, K = 3
+Arr[] = {1, 23, 12, 9, 30, 2, 50}
+Output: 50 30 23
+Explanation: 3 Largest element in the
+array are 50, 30 and 23.
+Your Task:
+You don't need to read input or print anything. Your task is to complete the function kLargest() which takes the array of integers arr, n and k as parameters and returns an array of integers denoting the answer. The array should be in decreasing order.
+
+Expected Time Complexity: O(N)
+Expected Auxiliary Space: O(K*logK)
+
+Constraints:
+1 ≤ K ≤ N ≤ 105
+1 ≤ Arr[i] ≤ 106
+ 
+*/
+
+vector<int> kLargest(int arr[], int n, int k)
+{
+  vector<int> ans;
+  priority_queue<int> pq;
+  for (int i = 0; i < n; ++i)
+    pq.push(arr[i]);
+
+  for (int i = 0; i < k; ++i)
+  {
+    ans.push_back(pq.top());
+    pq.pop();
+  }
+
+  return ans;
+}