src/fundamentals/leftrotate.js
/**
* -> https://en.wikipedia.org/wiki/Tree_rotation
*
* A B
* / \ / \
* a B -> A c
* / \ / \
* b c a b
*/
export default function leftrotate ( A ) {
const B = A.right;
A.right = B.left;
B.left = A;
return B;
}