我试图在Javascript中实现Quick-Sort,而没有引用psuedo代码。这是正确的实现吗?如果没有,我该如何改进。
const quickSort = (arr = []) => {
const length = arr.length;
if (length === 0 || length === 1) {
return arr;
}
const pivot = arr[0];
const leftArray = [];
const rightArray = [];
for (let i = 1; i < length; i++) {
if (arr[i] < pivot) {
leftArray.push(arr[i]);
} else {
rightArray.push(arr[i]);
}
}
return [...quickSort(leftArray), pivot, ...quickSort(rightArray)];
};
console.log(quickSort([2, 45, 6, 7, 8, 1]));
我已经添加了测试用例的代码,并执行了超过250000次。
// Function to generate random array.
const generateRandomArray = n =>
Array.from({
length: n
}, () => Math.floor(Math.random() * n));
// Function to check whether array is sorted.
const checkSorted = (arr = []) => {
let sorted = true;
for (let i = 1; i < arr.length; i++) {
if (arr[i] < arr[i - 1]) {
sorted = false;
break;
}
}
return sorted;
};
// Testing Quick-Sort
const testQuickSort = () => {
for (let i = 1; true; i++) {
const sortedArray = quickSort(generateRandomArray(Date.now() % 100000));
const isSorted = checkSorted(sortedArray);
if (!isSorted) {
console.log("error");
break;
}
console.log("pass", i);
}
};
testQuickSort();
您可以尝试以下解决方案
function pivot(arr, start = 0, end = arr.length - 1) {
const swap = (arr, idx1, idx2) => {
[arr[idx1], arr[idx2]] = [arr[idx2], arr[idx1]];
};
// We are assuming the pivot is always the first element
let pivot = arr[start];
let swapIdx = start;
for (let i = start + 1; i <= end; i++) {
if (pivot > arr[i]) {
swapIdx++;
swap(arr, swapIdx, i);
}
}
// Swap the pivot from the start the swapPoint
swap(arr, start, swapIdx);
return swapIdx;
}
function quickSort(arr, left = 0, right = arr.length -1){
if(left < right){
let pivotIndex = pivot(arr, left, right) //3
//left
quickSort(arr,left,pivotIndex-1);
//right
quickSort(arr,pivotIndex+1,right);
}
return arr;
}
console.log(quickSort([100,-3,2,4,6,9,1,2,5,3,23]));