Problem Description
Given an array of integers nums and an integer target, return indices of the two numbers in nums such that they add up to target.
You may assume that each input would have exactly one solution, and you may not use the same element twice.
Example 1:
Input: nums = [2,7,11,15], target = 9 Output: [0,1] Explanation: Because nums[0] + nums[1] = 2 + 7 = 9, we return [0, 1].
Example 2:
Input: nums = [3,2,4], target = 6 Output: [1,2]
Solution
function twoSum(nums: number[], target: number): number[] {
const map = new Map();
for (let i = 0; i < nums.length; i++) {
const complement = target - nums[i];
if (map.has(complement)) {
return [map.get(complement), i];
}
map.set(nums[i], i);
}
return [];
}Video Explanation
Time Complexity
O(n) - We traverse the array only once
Space Complexity
O(n) - We store at most n elements in the hash map