Move Zeros logic break down Javascript-CodePudding

I am working through this solution that I saw in this discussion section of leetcode and am unable to grasp part of the logic. The name of the game is to move all zeros to the end of a given array in place while maintaining the order of the other numbers. The increment operator inside the index of j is where I am lost because wouldn't that place the non-zero number to the right?

var moveZeroes = function(nums) {
    let j = 0
    for(let i = 0; i < nums.length; i  ) {
       if(nums[i] !== 0) {
           //storing the index we are iterating on
           let n = nums[i]
           //changing the index in place to 0
           nums[i] = 0
           //console.log(nums);
           // 
           nums[j  ] = n
           console.log(nums);
       }
   }
   return nums;
};

console.log(moveZeroes([0,1,0,3,12]));

CodePudding user response：

Remember that j is post-increment, so the initial value of j is used to index nums and then j is incremented. If it was j then j would be incremented first, then used.

CodePudding user response：

Try using Array.filter() to separate zeroes (ex. num === 0) and numbers that are not zeroes (ex. num !== 0) into two new and separate arrays. Then use either Array.concat() or the spread operator to merge them into a single array.

Details commented in the code below

// log() is an optional utility function that formats console logs
const log = data => console.log(`[${data}]`);

// This input array has zeroes everywhere
const numbers = [0, 1, 0, 0, 3, 0, 12];

const moveZeroes = array => {
  // With the given array called "numbers"
  // left = [1, 3, 13]
  const left = array.filter(num => num !== 0);
  // right = [0, 0, 0, 0]  
  const right = array.filter(num => num === 0);
  // Then arrays "left" and "right" are merged
  return [].concat(left, right)
};

log(moveZeroes(numbers));

CodePudding user response：

Simply Remove All Zeros. Add Removed Zeros to the end.

var moveZeroes = (nums) =>
  (
    nums.toString().replaceAll("0,", "")  
    ",0".repeat((""   nums).replace(/[^0]/g, "").length)
  )
    .split(",")
    .map(Number);
console.log(moveZeroes([0, 1, 0, 0, 3, 0, 12])); //[ 1, 3, 12, 0, 0, 0, 0 ]

NOTE:

("" nums).replace(/[^0]/g,'').length: number of 0 in the Array
nums.toString(): To convert array to string we use or we could use the trick of concatenating with an empty string like "" nums
split(','): To convert string into an array
map(Number): To convert an array of strings to numbers.