LeetCode solutions explanation JavaScript. Problem #1 - Two Sum explained solution

Опубликовано: 18 Октябрь 2024
на канале: Travels Code

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In this video, we will see LeetCode Two Sum problem solution with detailed explanation. Language - JavaScript.
There are 3 ways to solve the problem. I'll show all of them and compare the difference.

Approach 1: Brute Force
Runtime: 116 ms, faster than 39.08% of JavaScript online submissions for Two Sum.
Memory Usage: 36.8 MB, less than 23.52% of JavaScript online submissions for Two Sum.
Complexity Analysis
Time complexity : O(n^2) For each element, we try to find its complement by looping through the rest of array which takes O(n) time. Therefore, the time complexity is O(n^2)
Space complexity : O(1).

Approach 2: Two-pass Hash Table (JS object)
Runtime: 72 ms, faster than 68.37% of JavaScript online submissions for Two Sum.
Memory Usage: 34.9 MB, less than 61.50% of JavaScript online submissions for Two Sum.
Complexity Analysis
Time complexity : O(n). We traverse the list containing nn elements exactly twice. Since the hash table reduces the look up time to O(1), the time complexity is O(n).
Space complexity : O(n). The extra space required depends on the number of items stored in the object, which stores exactly n elements.

Approach 3: One-pass Hash Table
Time complexity : O(n). We traverse the list containing nn elements only once. Each look up in the table costs only O(1) time.
Space complexity : O(n). The extra space required depends on the number of items stored in the Map object, which stores at most nn elements.
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