Percolation is an algorithmic general strategy to move an element up or down in the 202112121746. It is primarily important for #202202071755.
When an element is needed to percolate up, it will first create a space in the deepest level of the tree. Until it found the correct place to settle, it will keep going up one level in the tree.
When an element is needed to percolate down, it will usually appear in the root of the tree. Until it found the correct place to settle, it will keep going down one level in the tree.