g1101_1200.s1157_online_majority_element_in_subarray

Class MajorityChecker

java.lang.Object

g1101_1200.s1157_online_majority_element_in_subarray.MajorityChecker

public class MajorityChecker
extends Object

1157 - Online Majority Element In Subarray.

Hard

Design a data structure that efficiently finds the majority element of a given subarray.

The majority element of a subarray is an element that occurs threshold times or more in the subarray.

Implementing the MajorityChecker class:

• MajorityChecker(int[] arr) Initializes the instance of the class with the given array arr.
• int query(int left, int right, int threshold) returns the element in the subarray arr[left...right] that occurs at least threshold times, or -1 if no such element exists.

Example 1:

Input [“MajorityChecker”, “query”, “query”, “query”] [[[1, 1, 2, 2, 1, 1]], [0, 5, 4], [0, 3, 3], [2, 3, 2]]

Output: [null, 1, -1, 2]

Explanation:

MajorityChecker majorityChecker = new MajorityChecker([1, 1, 2, 2, 1, 1]); majorityChecker.query(0, 5, 4); // return 1 majorityChecker.query(0, 3, 3); // return -1 majorityChecker.query(2, 3, 2); // return 2

Constraints:

• 1 <= arr.length <= 2 * 104
• 1 <= arr[i] <= 2 * 104
• 0 <= left <= right < arr.length
• threshold <= right - left + 1
• 2 * threshold > right - left + 1
• At most 104 calls will be made to query.

Constructor Summary

Constructors

Constructor and Description
MajorityChecker(int[] arr)

Method Summary

Modifier and Type	Method and Description
int	query(int left, int right, int threshold)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MajorityChecker

public MajorityChecker(int[] arr)

Method Detail

query

public int query(int left,
                 int right,
                 int threshold)