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
numsand an integertarget, return indices of the two numbers such that they add up totarget. - 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
-
statickeyword is used to define a static method for a class. -
staticmethods 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 thethisvalue 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>
Top comments (2)
Bind doesn't just allow setting the this.
It's full on partial application.
Each time it's called it returns a new function with the new bound args appended to the previously bound args.
If something takes multiple arguments, you can use bind to only provide some of them, and later call it with the remaining ones which can be useful for scoping data, or for having functions that accept infinite arguments that you want to be able to apply from different places so that the end user just calls with the ones they are adding every time.
Thank you for the information