Day 7 of #100DaysOfCode

What I learned?

I learned the following topics:

use of Static keyword in javascript
bind keyword in javascript

What I developed/solved?

Solved one leetcode problem called Two sum

Code snippet/Screenshots/notes

Leetcode problem Two sum

Problem statement: Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.
Example.

Input: nums = [2,7,11,15], target = 9
Output: [0,1]

Input: nums = [3,2,4], target = 6
Output: [1,2]

Brute force approach

class Solution {
public:
    vector<int> twoSum(vector<int>& nums, int target) {
        int size = nums.size();
        vector<int> ans;
        for (int i = 0; i < size; i++) {
            int flag = 0;
            for (int j = i+1; j < size; j++) {
            /* when the summation of these two becomes equal or up to target
               return the indexes of both
            */
                int sum = nums[j] + nums[i];
                if (sum == target && i != j){
                   ans.push_back(i);
                   ans.push_back(j);
                   /* flag used to determine that we have found 
                   that element whose summmation is equal to target
                    */
                   flag = 1;
                }
            }
            //flag = 1 meaning we got our answer so no need to go further
            if(flag == 1){
                break;
            }
        }
        return ans;
    }
};
// Time complexity: O(n)*O(n)=O(n^2)
// Space comlexity: O(1) as we aren't using extra space

optimal approach using hashmap

class Solution {
public:
    vector<int> twoSum(vector<int>& nums, int target) {
        map<int, int> m;
        vector<int> v;
        for (int i = 0; i < nums.size(); i++) {
            int first = nums[i];
            int second = target - first;

            if (m.find(second) != m.end()) {
                v.push_back(m[second]);
                v.push_back(i);
            }

            m[first] = i;
        }

        return v;
    }
};
/* Time complexity: O(N * logN), where n = number of elements in an array
logN = time takes for insertion in map
   Space complexity: O(N)
*/

Static keyword in JavaScript

static keyword is used to define a static method for a class.
static methods aren't called on instances of the class. Instead, they're called on the class itself.
You call it on the class, but on the instances of class

Bind keyword

bind() method in JavaScript is a method that allows you to set the this value in a function.

<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Bind</title>
</head>

<body>
    <button>Click me</button>
</body>

<script>
    class React {
        constructor() {
            this.library = "React"
            this.server = "https://localhost:3000"

            document.querySelector('button')
                .addEventListener('click', this.handleClick.bind(this)) //this for current context
        }

        handleClick() {
            console.log("button clicked successfully!")
            console.log(this.server)
        }
    }

    const my_app = new React();
</script>

</html>

Blog

Day 7 of #100DaysOfCode

Ashish Prajapati

What I learned?

What I developed/solved?

Code snippet/Screenshots/notes

Static keyword in JavaScript

Bind keyword

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