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Selection Sort

Selection sort animation

  • In-place comparison sort
  • Inefficient for large lists
  • Generally worse than insertion sort

Complexity

Average Time Space
O(n2)O(n^2) O(1)O(1)

Process

  • Find the smallest element in an array
  • Swap it with the first unordered element

Implementation

JavaScript

function selectionSort(array) {
  // Loop through the array
  for (let i = 0; i < array.length - 1; i++) {
    // Keep track of unsorted elelment
    let minIndex = i;

    // Loop through the rest of the array to find the smallest element
    for (let j = i + 1; j < array.length; j++) {
      // Smaller element found so update min
      if (array[j] < array[minIndex]) {
        minIndex = j;
      }
    }

    // Smallest element isn't the one we are at, swap them
    if (minIndex !== i) {
      [array[i], array[minIndex]] = [array[minIndex], array[i]];
    }
  }

  return array;
}

Computer Science Algorithm