In Java

Given an array A of n integers, a leader element of the array A is the element that appears more than half of the time in A.

Implement in Java an O(n) worst-case algorithm that uses a stack

static int leader(int[] A)

to find a leader element and return the index (any) of the leader in A. The program must returns -1 if no leader element exists.

Examples:

int[] a = {23, 23, 67, 23, 67, 23, 45}; ====> leader(a) = 5

int[] a = {23, 24, 67, 23, 67, 23, 45}; ====> leader(a) = -1