Easy
Find K-th largest element in N arrays.
Notice
You can swap elements in the array
Have you met this question in a real interview? Yes
Example
In n=2 arrays [[9,3,2,4,7],[1,2,3,4,8]], the 3rd largest element is 7.
In n=2 arrays [[9,3,2,4,8],[1,2,3,4,2]], the 1st largest element is 9, 2nd largest element is 8, 3rd largest element is 7 and etc.
这道题用了minHeap, 暴力地将每个数组元素都放到了minHeap里，然后再poll()出来让heap里只剩下k个。从剩下的k个里peek()出来的就是在整个数组里第k大的元素，即为所求。
public class Solution {
/*
* @param arrays: a list of array
* @param k: An integer
* @return: an integer, K-th largest element in N arrays
*/
public int KthInArrays(int[][] arrays, int k) {
// write your code here
PriorityQueue<Integer> pq = new PriorityQueue<>();
for (int i = 0; i < arrays.length; i++){
for (int j = 0; j < arrays[i].length; j++){
pq.add(arrays[i][j]);
}
}
while (pq.size() > k){
pq.poll();
}
return pq.peek();
}
}
