K Largest Element LeetCode

 Approach 1:

Using ArrayList and Sorting 

 

TIME : O(NLOGN) [LeetCode Time: 5 ms]

SPACE: O(N)             [LeetCode Space 39.2MB]

class Solution {

    public int findKthLargest(int[] arr, int k) {

        ArrayList<Integer> aa=new ArrayList<Integer>();

        for(int i=0;i<arr.length;i++){

            aa.add(arr[i]);

        }

        Collections.sort(aa);

        return (aa.get(aa.size()-k));

    }

}

=========================================================================

Approach 2:

Using Priority Queue and getting the peak element

TIME: O(NLOGK) [LeetCode Time: 2ms]

SPACE: O(K)           [LeetCode Space: 39.8MB]

class Solution {

    public int findKthLargest(int[] arr, int k) {

        PriorityQueue<Integer> q=new PriorityQueue<Integer>();

for(int i=0;i<k;i++){

q.add(arr[i]);

}

for(int i=k;i<arr.length;i++){

if(q.peek()<arr[i]){

q.remove();

q.add(arr[i]);

}

}

        return q.peek();

    }

}

Thanks for Reading.

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