Next Greater Element

class Solution {

public ArrayList nextLargerElement(int[] arr) {

int n = arr.length;

int[] result = new int[n];

Stack stack = new Stack<>();

for (int i = n - 1; i >= 0; i--) {

while (!stack.isEmpty() && stack.peek() <= arr[i]) {

stack.pop();

}

result[i] = stack.isEmpty() ? -1 : stack.peek();

stack.push(arr[i]);

}

// Convert array to ArrayList

ArrayList list = new ArrayList<>();

for (int val : result) { list.add(val);

}

return list;

}

}