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leetcode.com/problems/two-sum
1. Two Sum
EasyArrayHash Table
Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.
Python3
1class Solution:
2def twoSum(self, nums, target):
3seen = {}
4for i, num in enumerate(nums):
5need = target - num
6if need in seen:
7return [seen[need], i]
8seen[num] = i
9return []
RunAccepted
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Two Sum
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Solution
1def twoSum(nums, target):
2seen = {}
3for i, num in enumerate(nums):
4need = target - num
5if need in seen:
6return [seen[need], i]
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arrayhash table
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The extension captures every problem as you solve it, and brings in the ones you solved before you installed it. You add the thinking, now or later.
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Open a problem and start solving. The extension picks up the problem, its difficulty, the link and your code, and saves them in the background. Write notes alongside as you go, or come back later and fill them in.
Now solvingCapturing
15. 3SumMedium
Problem, difficulty and linkjust now
Your codePython3 · 14 lines
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Two PointersArraysSortingAdd to review
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Ttaylorkim · leetcode.comConnected
Imported 0 solved problems0%
Imported 228 · Skipped 3 that already had your notes
146. LRU CacheMediumcode imported
Add notesAdd to review
200. Number of IslandsMediumcode imported
On review plan
42. Trapping Rain WaterHardcode imported
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The extension captures. The web app organizes, reviews and exports.
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Write what you remember, reveal your notes, then mark it Forgot it, Shaky or Got it.
Card 3 of 13
3Sum
Mediumtwo pointersNoted 15 days ago
Before you look: what's the approach?
Sort first. Fix nums[i], two pointers on the rest, skip duplicates. O(n²).
Reveal my notes
Forgot itShakyGot it
Up next13 due
3SumNow
Coin ChangeShaky last time
Number of IslandsForgot last time
Valid ParenthesesDue today
Trapping Rain WaterDue today
Shaky and forgotten cards come back first.
Import what you've solved
Chrome extension only. Bring in every problem you've solved on leetcode.com, then add notes or put it on your review plan.
Ttaylorkim · leetcode.comConnected
Importing…0%
Your latest Accepted solution for every solved problem. Notes you already wrote are left alone.
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0notes
array
two pointers
hash table
dynamic programming
Learning paths
Basics to LeetCode 150, with the problems you've already noted checked off.
ComplexityRead
Arrays2 / 3
Strings2 / 3
Hash Maps0 / 2
Linked Lists2 / 2
Stacks1 / 1
Queues0 / 1
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A scratchpad to try an idea before you commit to it.
JavaScriptRun
1const seen = new Map();
2for (let i = 0; i < nums.length; i++) {
3if (seen.has(t - nums[i])) return …
4}
[ 0, 1 ]exit 0
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