target-sum

Author: bap2pecs0

Facebook/Ninja/123456789.py

@@ -0,0 +1,133 @@
+'''
+Question:
+123456789 = 100 (also known as targetSum)
+Using standard integer arithmeric operators +, -, how many different solutions
+can you find by inserting the operators between some digits?
+
+Solutions;
+123-45-67+89 = 100
+123-4-5-6-7+8-9 = 100
+123+45-67+8-9 = 100
+123+4-5+67-89 = 100
+12-3-4+5-6+7+89 = 100
+12+3-4+5+67+8+9 = 100
+12+3+4+5-6-7+89 = 100
+1+23-4+56+7+8+9 = 100
+1+23-4+5+6+78-9 = 100
+1+2+34-5+67-8+9 = 100
+1+2+3-4+5+6+78+9 = 100
+-1+2-3+4+5+6+78+9 = 100
+
+'''
+
+class Tree:
+    def __init__(self, data: str) -> None:
+        self.data = data
+        self.left = None
+        self.right = None
+        self.middle = None
+
+class SolutionOne(object):
+    def __init__(self, digits: str, target: int) -> None:
+        self.digits = digits
+        self.target = target
+
+    def strToRes(self, s: str) -> int:
+        """
+        examples:
+        '#-1#+2#-234#+6' -> -227
+        '1#+2#-234#+6' -> -225
+        """
+        numbers = s.split('#')
+        if numbers[0] == '':
+            return sum([int(x) for x in numbers[1:]])
+        else:
+            return sum([int(x) for x in numbers])
+
+    def evalAndPrint(self, s: str) -> None:
+        if self.strToRes(s) == self.target:
+            print(
+                s.translate(str.maketrans('', '', '#')) + 
+                ' = ' + 
+                str(self.target)
+            )
+
+    def targetSum(self) -> None:
+        root = Tree(None)
+        self.createTree(root, 0, len(self.digits))
+        self.tranverse(root, '', self.digits)
+
+    def createTree(self, root: Tree, cur: int, depth: int) -> None:
+        if cur == 0:
+            root.left = Tree('')
+            root.right = Tree('#-')
+            self.createTree(root.left, cur+1, depth)
+            self.createTree(root.right, cur+1, depth)
+        elif cur < depth:
+            root.left = Tree('')
+            root.right = Tree('#-')
+            root.middle = Tree('#+')
+            self.createTree(root.left, cur+1, depth)
+            self.createTree(root.right, cur+1, depth)
+            self.createTree(root.middle, cur+1, depth)
+
+    def tranverse(self, tree: Tree, cur_path: str, digits: str) -> None:
+        if cur_path == '':
+            self.tranverse(
+                tree.left,
+                cur_path + tree.left.data + digits[0],
+                digits[1:],
+            )
+            self.tranverse(
+                tree.right,
+                cur_path + tree.right.data + digits[0],
+                digits[1:],
+            )
+        elif tree.left == None and tree.middle == None and tree.right == None:
+            self.evalAndPrint(cur_path)
+        else:
+            self.tranverse(
+                tree.left,
+                cur_path + tree.left.data + digits[0],
+                digits[1:],
+            )
+            self.tranverse(
+                tree.right,
+                cur_path + tree.right.data + digits[0],
+                digits[1:],
+            )
+            self.tranverse(
+                tree.middle,
+                cur_path + tree.middle.data + digits[0],
+                digits[1:],
+            )
+
+class SolutionTwo(object):
+    def __init__(self, digits: str, target: int) -> None:
+        self.digits = digits
+        self.target = target
+
+    def evalAndPrint(self, s: str) -> None:
+        if eval(s) == self.target:
+            print(s + ' = ' + str(self.target))
+
+    def targetSum(self) -> None:
+        self.step('', 0)
+
+    def step(self, path: str, i: int) -> None:
+        if i >= len(self.digits):
+            self.evalAndPrint(path)
+            return
+
+        self.step(path + '' + self.digits[i], i+1)
+        self.step(path + '-' + self.digits[i], i+1)
+
+        if i != 0:
+            self.step(path + '+' + self.digits[i], i+1)
+
+if __name__ == '__main__':
+    print('=== solution 1 ===')
+    SolutionOne('123456789', 100).targetSum()
+
+    print('=== solution 2 ===')
+    SolutionTwo('123456789', 100).targetSum()