What is bubble sort

Bubble sorting is a simple but inefficient sorting algorithm. Its principle is to gradually "bubble" the largest element to the end of the array through comparison and exchange of adjacent elements. The time complexity of bubble sort is O(n^2), where n is the length of the array to be sorted. Detailed introduction: Starting from the first element of the array, compare the two adjacent elements in sequence. If the previous element is greater than the latter element, swap their positions. After one round of comparison, the largest element will "bubble" Go to the end of the array, start from the first element of the array, repeat the above operation, and so on.

The operating system for this tutorial: Windows 10 system, DELL G3 computer.

Bubble sort is a simple but inefficient sorting algorithm. Its principle is to gradually "bubble" the largest element to the end of the array through comparison and exchange between adjacent elements. The time complexity of bubble sort is O(n^2), where n is the length of the array to be sorted.

The implementation idea of ​​bubble sorting is very simple. First, starting from the first element of the array, compare the two adjacent elements in sequence. If the former element is greater than the latter element, swap their positions. After this round of comparison, the largest element will "bubble" to the end of the array. Then, starting from the first element of the array, repeat the above comparison and exchange process until all elements are arranged in order from small to large.

The following is a sample code for bubble sorting:

void bubbleSort(int arr[], int n) {
    for (int i = 0; i < n-1; i++) {
        for (int j = 0; j < n-i-1; j++) {
            if (arr[j] > arr[j+1]) {
                // 交换arr[j]和arr[j+1]的位置
                int temp = arr[j];
                arr[j] = arr[j+1];
                arr[j+1] = temp;
            }
        }
    }
}

The advantages of bubble sorting are simple implementation and clear logic, and only need to use an additional variable to exchange elements. However, the shortcomings of bubble sort are also obvious. Its time complexity is high, especially when processing large-scale data, and its efficiency is very low. Since only one element can be placed in the correct position in each round, n-1 rounds of comparison and exchange operations are required, which results in the time complexity of bubble sorting being O(n^2).

In order to improve the efficiency of bubble sorting, an optimization strategy can be introduced, which is to set a flag bit to determine whether exchange has occurred in each round of comparison. If no exchange occurs in a certain round of comparison, it means that the array is already in order and the sorting can be ended early. This can reduce unnecessary comparison and exchange operations and improve sorting efficiency.

In short, although bubble sort is simple and easy to understand, it is rarely used in practical applications because it is less efficient. When processing large-scale data, the more commonly used sorting algorithms are quick sort, merge sort, etc. However, understanding the principle and implementation process of bubble sort is also helpful for learning and understanding other sorting algorithms.

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