Given an array arr[] consisting of only 0s, 1s, and 2s. Sort the array, i.e., put all 0s first, then all 1s and all 2s in last.

Hint

Go through the entire list and count how many times each number (0, 1, and 2) appears. Create a new list by filling it with the correct number of 0s, then 1s, and finally 2s based on the counts.

# Python implementation

ls = [1, 2, 1, 0, 0, 2, 1, 1, 0]
zero = 0
one = 0
two = 0

for item in ls:
  if item == 0:
    zero += 1
  elif item == 1:
    one += 1
  elif item == 2:
    two += 1

print([0] * zero +  [1] * one + [2] * two)

// Javascript implementation

const list = [1, 2, 1, 0, 0, 2, 1, 1, 0];

let zero = 0;
let one = 0;
let two = 0;

for (let i of list) {
  if (i === 0) {
    zero++;
  }

  if (i === 1) {
    one++;
  }

  if (i === 2) {
    two++;
  }
}

console.log([...Array(zero).fill(0), ...Array(one).fill(1), ...Array(two).fill(2)]);

Sort an array of 0s, 1s and 2s

Hint