[PHP知识库]经典算法记录

选择排序

function _selectionSort(arr) {
    let temp;
    for (var i = 0; i < arr.length - 1; i++) {
        let idx = i;
        for (var j = i + 1; j < arr.length; j++) {
            if (arr[j] < arr[idx]) {
                idx = j
            }
        }
        temp = arr[i]
        arr[i] = arr[idx]
        arr[idx] = temp
    }
    console.log(arr)
}

a = [6, 3, 1, 7, 8, 2, 4]
_selectionSort(a)

冒泡排序

function _bubbleSort(arr) {
    let len = arr.length
    for (var i = 0; i < len - 1; i++) {
        for (var j = 0; j < len - 1; j++) {
            if (arr[j] > arr[j + 1]) {
                let t = arr[j]
                arr[j] = arr[j + 1]
                arr[j + 1] = t
            }
        }
    }
    console.log(arr)
}

a = [3, 1, 2, 4]
_bubbleSort(a)

快速排序

var a = [6, 3, 1, 2, 5, 4];

function _paritition(nums, l, r) {
    let pivot = nums[l];
    while (l < r) {
        while (l < r && nums[r] >= pivot) {
            r--;
        }
        nums[l] = nums[r];

        while (l < r && nums[l] <= pivot) {
            l++;
        }
        nums[r] = nums[l];
    }
    nums[l] = pivot;
    return l;
}

function quickSort(nums, l, r) {
    if (l < r) {
        let middle = _paritition(nums, l, r);
        quickSort(nums, l, middle - 1);
        quickSort(nums, middle + 1, r);
    }
    return nums;
}

var res = quickSort(a, 0, 5);
console.log(res);

快速排序（PHP）

$a = [1, 6, 2, 7, 9, 3, 4, 5, 10, 8];

function qsort($nums)
{
    if (count($nums) <= 1) {
        return $nums;
    }

    $_left = [];
    $_right = [];
    $middle = $nums[0];
    $len = count($nums) - 1;
    for ($i = $len; $i > 0; $i--) {
        if ($nums[$i] > $middle) {
            array_push($_right, $nums[$i]);
        } else {
            array_push($_left, $nums[$i]);
        }
    }

    $_left = qsort($_left);
    $_left[] = $middle;
    $_right = qsort($_right);
    return array_merge($_left, $_right);
}