为期五天刷题打卡 9-28 ~10-2

打算从头捡起刷题..
9-28基本上跟着答案写了
containsDuplicate
mergeSortedArray
moveZeroes
reverseString
twoSum

note:
可以用系统自带的类型 比如set来判断array里面有没有重复的 e.g. new Set(nums)
一定要记得判断input valid不valid 为不为空
语言自带的function也可以用 .reverse().join("") 一类的,也算多解的一种方法

9-29
1480. Running Sum of 1d Array
firstReccuringNum
shuffleArray
greatestNumofCandies

note:
native methods such as Math.max and destructing can be helpeful
think about space and time trade off
you may just modify the input instead of creating a new variable

9-30

implemented linkedlist, stack, queue in native javascript
you understand more when you implement it yourself.

10-1

LC232 implement queue with stack
LC349 IntersectionofTwoArray




Note:
use two stacks to implement queue
new Set() and use new set to filter against array2

10-2
OA // write a code to move all the negative numbers before all positive numbers in an Array. The order of the numbers in a array must be same.
// eg. input is [5,2,7,-4,3,-8,-10] output: [-4,-8,-10,5,2,7,3];
const input = [5, 2, 7, -4, 3, -8, -10];
const processArray = (arr) => {
  let counter = 0;
  for (let i = 0; i < arr.length; i++) {
    if (arr[i] < 0) {
      arr.splice(counter, 0, arr[i]);
      arr.splice(i + 1, 1);
      counter++;
    }
  }
};
processArray(input);
console.log(input);

LC 433 string compression

Note:
learnt splice, slice methods
had more thoughts on structures to use.