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Array Reversal and Two Sum Problem Solutions

Array Reversal:

Implemented a function to reverse an array in-place. This method swaps elements from both ends of the array towards the center, effectively reversing the array with a time complexity of O(n) and space complexity of O(1).

Two Sum Problem:

Developed a solution for the two-sum problem, identifying indices of the two numbers in an array that add up to a specific target. Using a map to track elements and their indices, this approach quickly finds the complement of the current element by checking if it exists in the map. The indices of the elements that sum up to the target are returned in reversed order, achieved by calling the array reversal function on the result array.

1function reverse(arr) {
2  let start = 0;
3  let end = arr.length - 1;
4  for (let i = 0; i < Math.floor(arr.length / 2); i++) {
5    [arr[start], arr[end]] = [arr[end], arr[start]];
6    end--;
7    start++;
8  }
9  return arr;
10}
11
12//TC = O(n), SC = O(n)
13var twoSum = function (nums, target) {
14  let m = new Map();
15  let element = [];
16  for (let i = 0; i < nums.length; i++) {
17    if (m.has(target - nums[i])) {
18      element.push(i);
19      element.push(m.get(target - nums[i]));
20    } else {
21      m.set(nums[i], i);
22    }
23  }
24  return reverse(element);
25};
26