mathjs/src/function/algebra/sparse/csTdfs.js

/**
 * Depth-first search and postorder of a tree rooted at node j
 *
 * @param {Number}  j               The tree node
 * @param {Number}  k
 * @param {Array}   w               The workspace array
 * @param {Number}  head            The index offset within the workspace for the head array
 * @param {Number}  next            The index offset within the workspace for the next array
 * @param {Array}   post            The post ordering array
 * @param {Number}  stack           The index offset within the workspace for the stack array
 *
 * Reference: http://faculty.cse.tamu.edu/davis/publications.html
 */
export function csTdfs (j, k, w, head, next, post, stack) {
  // variables
  let top = 0
  // place j on the stack
  w[stack] = j
  // while (stack is not empty)
  while (top >= 0) {
    // p = top of stack
    const p = w[stack + top]
    // i = youngest child of p
    const i = w[head + p]
    if (i === -1) {
      // p has no unordered children left
      top--
      // node p is the kth postordered node
      post[k++] = p
    } else {
      // remove i from children of p
      w[head + p] = w[next + i]
      // increment top
      ++top
      // start dfs on child node i
      w[stack + top] = i
    }
  }
  return k
}