What I learned?
I learned the following topics:
getOwnPropertyDescriptormethod in JSdefinePropertymethod in JS- Iteratng through Object
What I developed/solved?
- Solved leetcode problem 75. Sort colors using Dutch national flag algorithm
Code snippet/Screenshots/notes
- Leetcode 75. Sort Colors
- Problem Statement: Given an array
numswithnobjects colored red, white, or blue, sort them in-place so that objects of the same color are adjacent - example.
Input: nums = [2,0,2,1,1,0]
Output: [0,0,1,1,2,2]
Input: nums = [2,0,1]
Output: [0,1,2]
- Better solution:
class Solution {
public:
void sortColors(vector<int>& nums) {
int cnt0 = 0; //stores the numbers of 0's
int cnt1 = 0; //stores the numbers of 1's
int cnt2 = 0; //stores the numbers of 2's
for(int i = 0; i<nums.size(); i++){
if(nums[i] == 0)cnt0++;
else if(nums[i] == 1)cnt1++;
else cnt2++;
}
//rewriting first cnt0 places in original array
for(int i = 0; i<cnt0; i++){
nums[i] = 0;
}
// rewriting cnt1 places after 0's in array
for(int i = cnt0; i<cnt0+cnt1; i++){
nums[i] = 1;
}
//rewriting cnt2 places after 1's
for(int i = cnt1+cnt2; i<cnt0+cnt1+cnt2; i++){
nums[i] = 2;
}
}
};
/*
Dry Run: nums = [2,0,2,1,1,0]
cnt0 = 2, cnt1 = 2, cnt2 = 2
range[0,2], two iterations
for(0 -> 2)
nums[0] = 0
nums[1] = 0
changed array: nums = [0, 0, 2, 1, 1, 0]
[cnt1, cnt0+cnt1]
range[2,4], two iterations
for(2 -> 4)
nums[2] = 1
nums[3] = 1
changed array: nums = [0, 0, 1, 1, 1, 0]
[cnt1+cnt2, cnt0+cnt1+cnt2]
range[4,6], two iterations
for(4 -> 6)
nums[4] = 2
nums[5] = 2
final Sorted Array: nums = [0, 0, 1, 1, 2, 2]
*/
- Optimal Solution using Dutch national flag Algorithm:
class Solution {
public:
void sortColors(vector<int>& nums) {
int low = 0;
int mid = 0;
int high = nums.size()-1;
while(mid <= high){
if(nums[mid] == 0){
swap(nums[mid], nums[low]);
low++;
mid++;
}
else if(nums[mid] == 1){
mid++;
}
else{
swap(nums[high], nums[mid]);
high--;
}
}
}
};
-
Object.getOwnPropertyDescriptor(): static method returns an object describing the configuration of a specific property on a given object
// example
const Descriptor = Object.getOwnPropertyDescriptor(Math, "PI");
/* this method takes two parameters (object, "property") */
console.log(Descriptor);
/*
{
value: 3.141592653589793,
writable: false,
enumerable: false,
configurable: false
}
*/
/* in this scenario Math.PI value can't be overwrite, because the writable and enumerable perperties set to false
*/
-
Object.defineProperty(): static method defines a new property directly on an object, or modifies an existing property on an object, and returns the object.
const user = {
name: "user",
email: "user@gmail.com",
password: "pwd"
}
console.log(Object.getOwnPropertyDescriptor(user, "email"))
/*
{
value: 'user@gmail.com',
writable: true,
enumerable: true,
configurable: true
}
*/
//can use defineProperties for changing multiple properties
Object.defineProperty(user, "email", {
writable: false,
enumerable: false,
configurable: false
})
console.log(Object.getOwnPropertyDescriptor(user, "email"))
/*
{
value: 'user@gmail.com',
writable: false,
enumerable: false,
configurable: false
}
*/
This is how you can iterate through object
for (let [key, value] of Object.entries(user)) {
if (typeof value !== "function") {
console.log(`${key} : ${value}`)
}
}
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