selection-sort.js

// selection-sort.js — Selection sort algorithm with visualization step tracking
// Extracted from sortingAlgorithms.js for single-responsibility.

/**
 * Selection sort — finds the minimum element and places it at the beginning.
 * Returns an array of step objects for animation.
 * @param {Array} arr - Array of {width, ...} objects to sort
 * @returns {Array} Array of {xx, yy, changed} step objects
 */
export function selectionSort(arr) {
    const pairs = [];
    let n = arr.length;
    const prevRect = arr.slice();
    // One by one move boundary of unsorted subarray
    for (let i = 0; i < n-1; i++)
    {
        let min_idx = i;
        for (let j = i+1; j < n; j++){
            pairs.push( {
                xx:min_idx,
                yy:j,
                changed:false
            } );
            if (prevRect[j].width < prevRect[min_idx].width){
                min_idx = j;
            }
        }

        // Swap the found minimum element with the first element
        const recti = {...prevRect[i]};
        const rectj = {...prevRect[min_idx]};
        prevRect[min_idx] = recti;
        prevRect[i] = rectj;
        pairs.push( {
            xx:min_idx,
            yy:i,
            changed:true
        } );
        pairs.push( {
            xx:i,
            yy:i,
            changed:false
        });
    }
    pairs.push({
            xx:n-1,
            yy:n-1,
            changed:false
        }
    )
    return pairs;
}