LeetCode 768

class Solution {
    public int maxChunksToSorted(int[] arr) {
        Deque<Integer> stk = new LinkedList<>();
        int n = arr.length;
        for (int i = 0; i < n; i++) {
            if (!stk.isEmpty() && arr[i] < arr[stk.peek()]) {
                int index = stk.peek();
                while (!stk.isEmpty() && arr[i] < arr[stk.peek()]) stk.pop();
                stk.push(index);
            } else stk.push(i);
        }
        return stk.size();
    }
}