[JS] 정렬 알고리즘

선택 정렬

const array = [7, 5, 9, 0, 3, 1, 6, 2, 4, 8];

for (let i = 0; i < array.length; i++) {
  let minIndex = i;
  for (let j = i + 1; j < array.length; j++) {
    if (array[minIndex] > array[j]) {
      minIndex = j;
    }
  }
  const temp = array[minIndex];
  array[minIndex] = array[i];
  array[i] = temp;
}

console.log(array);

---

삽입 정렬

const array = [7, 5, 9, 0, 3, 1, 6, 2, 4, 8];

for (let i = 1; i < array.length; i++) {
  for (let j = i; j > 0; j--) {
    if (array[j] < array[j - 1]) {
      const temp = array[j];
      array[j] = array[j - 1];
      array[j - 1] = temp;
    } else {
      break;
    }
  }
}

console.log(array);

---

퀵 정렬

const array = [7, 5, 9, 0, 3, 1, 6, 2, 4, 8];

function quickSort(array, start, end) {
  if (start >= end) {
    return;
  }

  pivot = start;
  left = start;
  right = end;

  while (left <= right) {
    while (left <= end && array[left] <= array[pivot]) {
      left += 1;
    }
    while (right > start && array[right] >= array[pivot]) {
      right -= 1;
    }
    
    if (left > right) {
      const temp = array[right];
      array[right] = array[pivot];
      array[pivot] = temp;
    } else {
      const temp = array[right];
      array[right] = array[left];
      array[left] = temp;
    }
  }

  quickSort(array, start, right - 1);
  quickSort(array, right + 1, end);
}

quickSort(array, 0, array.length - 1);
console.log(array);

---

계수 정렬

const array = [7, 5, 9, 0, 3, 1, 6, 2, 9, 1, 4, 8, 0, 5, 2];

const count = new Array(Math.max(...array) + 1).fill(0);

for (let i = 0; i < array.length; i++) {
  count[array[i]] += 1;
}

let result = '';
for (let i = 0; i < count.length; i++) {
  for (let j = 0; j < count[i]; j++) {
    result += i + ' ';
  }
}

console.log(result);