evaluateExp

kata.go

package kata

import (
    "rachel/tree"
)

func EvaluateExp(s string) int {
    count := 0
    trees := tree.FullBinaryTreesFor(s)
    for _, tree := range trees {
        if evalBinaryTree(tree) {
            count ++
        }
    }
    return count
}

func evalBinaryTree(tree *tree.BinaryTree) bool {
    if tree.Left == nil && tree.Right == nil {
        return tree.Value == 'T'
    }

    switch tree.Value {
    case '&':
        return evalBinaryTree(tree.Left) && evalBinaryTree(tree.Right)
    case '|':
        return evalBinaryTree(tree.Left) || evalBinaryTree(tree.Right)
    case '^':
        return evalBinaryTree(tree.Left) != evalBinaryTree(tree.Right)
    }
    return false
}

tree.go

package tree

type BinaryTree struct {
    Value byte
    Left *BinaryTree
    Right *BinaryTree
}

func FullBinaryTreesFor(s string) []*BinaryTree {
    length := len(s)
    if length == 1 {
        return []*BinaryTree{&BinaryTree{Value: s[0]}}
    }

    var result []*BinaryTree
    for i := 0; i < (length-1)/2; i++ {
        e := i*2+1 // Odd index
        ltrees := FullBinaryTreesFor(s[:e])
        rtrees := FullBinaryTreesFor(s[(e+1):])
        for _, ltree := range ltrees {
            for _, rtree := range rtrees {
                result = append(result, &BinaryTree{s[e], ltree, rtree})
            }
        }
    }

    return result
}

Love that you used binary trees!!

Love that you used binary trees!!

Thanks @cassidoo, you're the best!! 🙌