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+"""
+Question
+
+Two Integer Sum
+
+Given an array of integers nums and an integer target, return the indices i and j such that nums[i] + nums[j] == target and i != j.
+
+You may assume that every input has exactly one pair of indices i and j that satisfy the condition.
+
+Return the answer with the smaller index first.
+
+Example 1:
+
+Input: 
+nums = [3,4,5,6], target = 7
+
+Output: [0,1]
+
+Explanation: nums[0] + nums[1] == 7, so we return [0, 1].
+
+Example 2:
+
+Input: nums = [4,5,6], target = 10
+
+Output: [0,2]
+
+Example 3:
+
+Input: nums = [5,5], target = 10
+
+Output: [0,1]
+
+Constraints:
+
+    2 <= nums.length <= 1000
+    -10,000,000 <= nums[i] <= 10,000,000
+    -10,000,000 <= target <= 10,000,000
+"""
+
+
+from typing import List
+
+
+class Solution:
+    def hashmap(self, nums: List[int], target: int) -> List[int]:
+        mp = {}
+        for i, n in enumerate(nums):
+            diff = target - n
+            if diff in mp:
+                return [mp[diff], i]
+            mp[nums[i]] = i
+        return [-1, -1]
+
+
+case1 = [3, 4, 5, 6]
+target1 = 7
+case2 = [4, 5, 6]
+target2 = 10
+case3 = [5, 5]
+target3 = 10
+
+solution = Solution()
+print(f" hashmap case1: {solution.hashmap(case1, target1)}")
+print(f" hashmap case2: {solution.hashmap(case2, target2)}")
+print(f" hashmap case3: {solution.hashmap(case3, target3)}")
+
+
+"""
+Solution
+
+url: https://neetcode.io/problems/two-integer-sum
+video: https://youtu.be/KLlXCFG5TnA
+code: 
+class Solution:
+    def twoSum(self, nums: List[int], target: int) -> List[int]:
+        prevMap = {}  # val -> index
+
+        for i, n in enumerate(nums):
+            diff = target - n
+            if diff in prevMap:
+                return [prevMap[diff], i]
+            prevMap[n] = i
+"""