JavaScript implements selection sort

Ideas

Take ascending order as an example:

1. Find the smallest value in the array and place it in the first place of the array
2. Find the second smallest value in the array and place it at the second place in the array
3. By analogy, the execution n-1round can complete the sorting

The ascending order selection and sorting animation demonstration is shown in the figure:

Time complexity : O(n ² )

achieve

Existing array [7, 5, 4, 15, 3, 9, 6, 12], sort in ascending order:

Array.prototype.selectionSort = function() {
    
    
    // 重复(元素个数-1)次
    for (let i = 0; i < this.length - 1; i++) {
    
    
        // 把第一个没有排序过的元素设置为最小值
        let indexMin = i;
        // 遍历每个没有排序过的元素
        for (let j = i; j < this.length; j++) {
    
    
            // 如果遍历时出现元素小于现在的最小值
            if (this[j] < this[indexMin]) {
    
    
                // 将此元素设置为新的最小值
                indexMin = j;
            }
        }
        // 遍历结束后，将最小值和第一个没有排序过的位置交换
        if (indexMin !== i) {
    
    
            let temp = this[i];
            this[i] = this[indexMin];
            this[indexMin] = temp;
        }
    }
};

const arr = [7, 5, 4, 15, 3, 9, 6, 12];
arr.selectionSort();
console.log(arr);

Results of the: