Minimum Swaps To Convert Binary Tree Into BST

link="https://www.codingninjas.com/codestudio/problems/minimum-swaps-to-convert-binary-tree-into-bst_1118109?leftPanelTab=1"
def minimumSwaps(arr: list, n: int):
    res=[]
    def inorder(i):
        if i>=n:return
        inorder(2*i+1)
        res.append(arr[i])
        inorder(2*i+2)
    inorder(0)
    count=0
    i=0
    items=[(j,i) for i,j in enumerate(res)]
    items.sort()

    while i<n:
        if items[i][1]==i:i+=1
        else:
            y=items[i][1]
            items[i],items[y]=items[y],items[i]
            count+=1
    return count