pseudocode - return sum of all non-leaf nodes, binary tree -


a binary tree can encoded using 3 functions: l, r , k such node n, l (n) gives left child of n (or nil if there none), r(n) gives right child of n (or nil if there none), , k(n) gives key value @ n.

let treesum(l, r, x, k) simple recursive algorithm takes binary tree encoded l, r, , k functions, root x, , returns sum of key values @ non-leaf nodes. give pseudocode algorithm.

however think this?

treesum(l,r,x,k)   if(l(n) number)   x = k(l(n)) + x      return treesum(l,r,x,k)  else if ( node leaf or not number)      return nil    if(r(n) number)     x = k(r(n)) + x         return treesum(l,r,x,k)  else if ( node leaf or not number)     return nil

not quite sure how go question. need find way non-leaf nodes , add values of nodes up.

this might work...

treesum(l,r,x,k)

if x == nil     k[x] = 0 else     sum = k[x] + treesum(l,r,l[x],k) + treesum(l,r,r[x],k) return sum

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