### Coding Interview questions set 6

Let's begin with set 6,

13)Given an array of integer nums and an integer target, return indices of the two numbers such that they add up to the target.

Assumptions: 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]

Output: Because nums + nums == 9, we return [0, 1].

Example 2:

Input: nums = [3,2,4], target = 6

Output: [1,2]

Solution:

`const twoSum = (nums, target) => {  const map = {};  for (let i = 0; i < nums.length; i++) {    const another = target - nums[i];    if (another in map) {      return [map[another], i];    }    map[nums[i]] = i;  }  return null;};`

You may also like these articles:

14)Given an array of numbers containing n distinct numbers in the range [0, n], return the only number in the range that is missing from the array.

Could you implement a solution using only O(1) extra space complexity and O(n) runtime complexity?

Example 1:

Input: nums = [3,0,1]

Output: 2
Explanation: n = 3 since there are 3 numbers, so all numbers are in the range [0,3].
2 is the missing number in the range since it does not appear in nums.

Solution:
`var missingNumber = function (nums) {    var sum = 0;    for (let i = 0; i < nums.length; i++) {      sum += i + 1 - nums[i];    }`

return sum;
};