static int[] slidingMax(int[] a,int k){if(k<=0||a.length==0) return new int[0];int n=a.length;int[] res=new int[Math.max(0,n-k+1)];java.util.ArrayDeque<Integer> dq=new java.util.ArrayDeque<>();for(int i=0;i<n;i++){while(!dq.isEmpty() && dq.peekFirst()<=i-k) dq.removeFirst();while(!dq.isEmpty() && a[dq.peekLast()]<=a[i]) dq.removeLast();dq.addLast(i);if(i>=k-1) res[i-k+1]=a[dq.peekFirst()];}return res;}