EquiLeader.java

class Solution {
    public int solution(int[] A) {
        int length = A.length;
        
        int leader = A[0];
        int votes = 1;
        
        //Boyer–Moore majority vote algorithm
        for (int i = 1; i < length; i++) {
            int digit = A[i];
            votes += digit == leader ? 1 : -1;
            if (votes == 0) {
                leader = digit;
                votes = 1;
            }
        }
        votes = 0;
        for (int i : A) {
            if (i == leader) {
                votes++;
            }
        }
        if (votes <= length/2) return 0;
        
        int count = 0;
        int equiVotes = 0;
        for (int i = 0; i < length; i++) {
            int digit = A[i];
            if (digit == leader) {
              equiVotes++;
              votes--;
            }
            if (equiVotes > (i+1)/2 && votes > (length - i -1)/2) {
                count++;
            }
        }
        return count;
    }
}