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4271369
NeetCode — Invert Binary Tree8:42
Solution
def invertTree(root):
    if not root:
        return None

    # Swap children
    root.left, root.right = \
        root.right, root.left

    invertTree(root.left)
    invertTree(root.right)

    return root
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1.Two SumEasy
Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.
Example:
Input: nums = [2,7,11,15], target = 9 Output: [0,1]
PythonJavaC++
class Solution:
    def twoSum(self, nums, target):
        seen = {}
        for i, n in enumerate(nums):
            diff = target - n
            if diff in seen:
                return [seen[diff], i]
            seen[n] = i
Test Results
Case 1: [2,7,11,15]
Case 2: [3,2,4]
Case 3: [3,3]
2/3 Passed
Progress

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49%
NeetCode 150
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30%
Blind 75
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NeetCode 250
25/250
🔥 14
Day Streak
121
Problems Solved
42h
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Activity
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