Adding solution of problems 103 and 107

Author: Garvit244

100-200q/103.py

@@ -0,0 +1,61 @@
+'''
+    Given a binary tree, return the zigzag level order traversal of its nodes' values. (ie, from left to right, then right to left for the next level and alternate between).
+
+    For example:
+    Given binary tree [3,9,20,null,null,15,7],
+
+        3
+       / \
+      9  20
+        /  \
+       15   7
+
+    return its zigzag level order traversal as:
+
+    [
+      [3],
+      [20,9],
+      [15,7]
+    ]
+'''
+
+# Definition for a binary tree node.
+# class TreeNode(object):
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+
+class Solution(object):
+    def zigzagLevelOrder(self, root):
+        """
+        :type root: TreeNode
+        :rtype: List[List[int]]
+        """
+
+        if not root:
+        	return []
+
+        queue = [(root, 0)]
+        levelMap = {}
+
+        while queue:
+        	node, level = queue.pop(0)
+        	if node.left:
+        		queue.append((node.left, level+1))
+        	if node.right:
+        		queue.append((node.right, level+1))
+
+        	if level in levelMap:
+        		levelMap[level].append(node.val)
+        	else:
+        		levelMap[level] = [node.val]
+
+        result = []
+        spiral = False
+        for key, value in levelMap.iteritems():
+            if spiral:
+                value = value[::-1]
+            result.append(value)
+            spiral = not spiral
+        return result

100-200q/107.py

@@ -0,0 +1,57 @@
+'''
+    Given a binary tree, return the bottom-up level order traversal of its nodes' values. (ie, from left to right, level by level from leaf to root).
+
+    For example:
+    Given binary tree [3,9,20,null,null,15,7],
+
+        3
+       / \
+      9  20
+        /  \
+       15   7
+
+    return its bottom-up level order traversal as:
+
+    [
+      [15,7],
+      [9,20],
+      [3]
+    ]
+'''
+
+# Definition for a binary tree node.
+# class TreeNode(object):
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+
+class Solution(object):
+    def levelOrderBottom(self, root):
+        """
+        :type root: TreeNode
+        :rtype: List[List[int]]
+        """
+
+        if not root:
+        	return []
+
+        queue = [(root, 0)]
+        levelMap = {}
+
+        while queue:
+        	node, level = queue.pop(0)
+        	if node.left:
+        		queue.append((node.left, level+1))
+        	if node.right:
+        		queue.append((node.right, level+1))
+
+        	if level in levelMap:
+        		levelMap[level].append(node.val)
+        	else:
+        		levelMap[level] = [node.val]
+
+        result = []
+        for key, value in levelMap.iteritems():
+        	result.append(value)
+        return result[::-1]