Practice Online Majority Element In Subarray

Read the task, work through the examples, and check your approach against the constraints. Use the original LeetCode task for coding and submissions.

Hard#1157

LeetCode Problem

Online Majority Element In Subarray

Array Binary Search Design Binary Indexed Tree Segment Tree

Problem Statement

MajorityChecker(arr) answers query(left,right,threshold) over inclusive indices. Return a value occurring at least threshold times, or -1. The threshold exceeds half the interval length, so at most one value qualifies. Practice approach: A segment tree can merge Boyer-Moore candidate/count summaries to propose a candidate. Store sorted occurrence indices per value and verify its true interval count with two binary searches. Candidate voting alone is insufficient: a candidate may exist without meeting the threshold. Test a strict-majority query that has no qualifying value.

Source: Online Majority Element In Subarray on LeetCode. Use the original task for its coding environment and submissions.

Examples

# Example 1

Input

["MajorityChecker","query","query","query"]
[[[4,4,7,4,7]],[0,4,3],[1,4,3],[2,2,1]]

Output

[null,4,-1,7]

Explanation

4 occurs three times in the full array but only twice in indices 1 through 4; a one-cell interval returns that cell.

Constraints

1 <= arr.length <= 2 * 10^4

1 <= arr[i] <= 2 * 10^4

0 <= left <= right < arr.length

threshold <= right-left+1 < 2*threshold

At most 10^4 query calls.

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