Algorithm Guidecomplexity: O(n²)

Selection Sort

An intuitive in-place algorithm that repeatedly finds the smallest (or largest) element and swaps it to the front.

01 Explore How It Works

Interactive Step-by-Step

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Selection Sort

선택 정렬을 시작합니다. 매 반복마다 미정렬 영역에서 최솟값을 찾아 앞으로 배치합니다.

Logic Node1 / 14

Live Python

1def selection_sort(arr):

# n: 8

2 n = len(arr)

3 for i in range(n):

4 min_idx = i

5 for j in range(i + 1, n):

6 if arr[j] < arr[min_idx]:

7 min_idx = j

8 arr[i], arr[min_idx] = arr[min_idx], arr[i]

9 return arr

02 Understand It Simply

For Everyone

🔑Analogy

Repeatedly pick the smallest of what remains and place it at the front.

💡In Plain Words

Finds the minimum each pass and fills from the front.

Few swaps, but always O(n²) comparisons.

📍Where It's Used

–When swap cost is high
–learning sorting concepts

03 Python Implementation

A clean, readable reference implementation of the core logic of Selection Sort.

core_implementation.py

def selection_sort(arr):
    n = len(arr)
    for i in range(n):
        min_idx = i
        for j in range(i + 1, n):
            if arr[j] < arr[min_idx]:
                min_idx = j
        arr[i], arr[min_idx] = arr[min_idx], arr[i]
    return arr