ts-ds-tool/src/algorithms/sort/mergeSort/mergeSort.ts

Data structure and algorithm of TypeScript

/**
 * 归并排序
 * @param arr
 * @param key
 */
export function mergeSort<T>(arr: Array<T>, key?: keyof T): Array<T>{
    if (!arr || !arr.length){
        return arr;
    }
    const len = arr.length;
    if (len < 2){
        return arr;
    }
    // tslint:disable-next-line:no-shadowed-variable
    function merge(left: Array<T>, right: Array<T>, key?: keyof T){
        const result = [];

        while (left.length > 0 && right.length > 0) {
            const leftLassThanEqualRight = key ? left[0][key] <= right[0][key] : left[0] <= right[0];
            if (leftLassThanEqualRight) {
                result.push(left.shift());
            } else {
                result.push(right.shift());
            }
        }

        while (left.length){
            result.push(left.shift());
        }

        while (right.length){
            result.push(right.shift());
        }

        return result;
    }
    const middle = Math.floor(len / 2),
        left = arr.slice(0, middle),
        right = arr.slice(middle);
    return merge(this.mergeSort(left, key), this.mergeSort(right, key), key);
}