(3) Selection and sorting of sorting algorithm

Ideas

Selective sorting is similar to the bubble sorting and insertion sorting routines mentioned earlier . They both divide the array into sorted and unsorted sub-arrays. The main difference lies in element selection and placement . Selection Sort from unsorted selected array minimum (or maximum) is placed in a sorted array after.

The following uses | to separate sorted and unsorted arrays, such as:
data to be sorted: 7, 0, 2, 8, 1 (the ordered array is empty at the beginning)

Sorting once :
0 | 7, 2, 8, 1 (put the smallest number 0 after the ordered array ())

Secondary sorting :
0, 1 | 7, 2, 8 (put the smallest number 1 into the ordered array (0))

Sort three times :
0, 1, 2 | 7, 8 (put the smallest number 2 into the ordered array (0, 1))

Four sorting :
0, 1, 2, 7 | 8 (put the smallest number 7 into the ordered array (0, 1, 2))

Five sorts :
0, 1, 2, 7, 8 (put the smallest number 8 into the ordered array ( 0, 1, 2, 7 ))

The time complexity of the selection sorting algorithm is O(n^2)

Implementation code:

void selectSorted(vector<int>& nums) {
    
    
	int len = nums.size();
	int index, temp;
	for (int i = 0; i < len; i++) {
    
    
		index = len - 1;
		for (int j = len - 2; j >= i; j--) {
    
    // 从i~len-1中获取最小元素的索引
			if (nums[index] > nums[j]) {
    
    	//这里是升序排序，若是要降序 把 '>' 改成 '<' 即可
				index = j;
			}
		}
		// 通过交换的方式，将未排序的最小值，放入已排序数组（0~i-1）最后
		temp = nums[index];
		nums[index] = nums[i];
		nums[i] = temp;
	}
}

end

If you want to know about other sorts, click here: Summary of Sorting Algorithms