js十大经典算法排序

visualgo算法排序可视化：https://visualgo.net/zh/

一、冒泡排序。

/**
 * 冒泡排序
 * @param {Array} arr - 数组
 * @returns {Array} - 排序好的数组
 */
 console.time('冒泡排序')
function bubbleSort(arr) {
    let len = arr.length;
    let temp;
    for (let i = 0; i < len; i++) {
        for (let j = 0; j < len - 1 - i; j++) {
        	// 如果后边的比较小，和前面的换下位置。
            if (arr[j] > arr[j + 1]) {
                temp = arr[j + 1];
                arr[j + 1] = arr[j];
                arr[j] = temp
            }
        }
    }
    return arr
}
let arr = [1, 2, 234, 235, 23452, 234525, 4, 2, 5]
console.log(bubbleSort(arr))
console.timeEnd('冒泡排序')

二、选择排序。

/**
 * 选择排序
 * @param {Array} arr - 数组
 * @returns {Array} - 排序好的数组
 */

console.time('选择排序')

function selectionSort(arr) {
    let len = arr.length;
    let temp, minIndex;
    for (let i = 0; i < len - 1; i++) {
        minIndex = i
        for (let j = i + 1; j < len; j++) {
            if (arr[j] < arr[minIndex]) {
                minIndex = j
            }
        }
        temp = arr[i];
        arr[i] = arr[minIndex];
        arr[minIndex] = temp
    }
    return arr
}
let arr = [1, 2, 234, 235, 23452, 234525, 4, 2, 5]
console.log(selectionSort(arr))
console.timeEnd('选择排序')

三、插入排序。

/**
 * 插入排序
 * @param {Array} arr
 * @returns {Array}
 */

console.time('插入排序')

function insertionSort(arr) {
    let len = arr.length;
    let preIndex, current;
    for (let i = 1; i < len; i++) {
        preIndex = i - 1;
        current = arr[i]

        while (preIndex >= 0 && arr[preIndex] > current) {
            arr[preIndex + 1] = arr[preIndex]
            preIndex--;
        }
        arr[preIndex + 1] = current
    }
    return arr
}
let arr = [1, 2, 234, 235, 23452, 234525, 4, 2, 5]
console.log(insertionSort(arr))
console.timeEnd('插入排序')

四、希尔排序。

/**
 * 希尔排序,优化版的插入排序
 * @param {Array} arr
 * @returns {Array}
 */

console.time('希尔排序')

function shellSort(arr) {
    let len = arr.length;
    let temp, gap = 1;
    while (gap < len / 3) {
        gap = gap * 3 + 1;
    }
    for (gap; gap > 0; gap = Math.floor(gap / 3)) {
        for (let i = gap; i < len; i++) {
            temp = arr[i];
            for (var j = i - gap; j >= 0 && arr[j] > temp; j -= gap) {
                arr[j + gap] = arr[j]
            }
            arr[j + gap] = temp
        }
    }
    return arr
}
let arr = [1, 2, 234, 235, 23452, 234525, 4, 2, 5]
console.log(shellSort(arr))
console.timeEnd('希尔排序')

五、归并排序

/**
 * 归并排序
 * @param {Array} arr
 * @returns {Array}
 */

console.time('归并排序')

function mergeSort(arr) {
    let len = arr.length;
    if (len << 2) {
        return arr;
    }
    let middle = Math.floor(len / 2),
        left = arr.slice(0, middle),
        right = arr.slice(middle);
    return merge(mergeSort(left), mergeSort(right))
}

function merge(left, right) {
    let result = [];
    while (left.length && right.length) {
        if (left[0] <= right[0]) {
            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
}


let arr = [1, 2, 234, 235, 23452, 234525, 4, 2, 5]
console.log(mergeSort(arr))
console.timeEnd('归并排序')

六、快速排序

/**
* 快速排序
* @param {Array} arr
* @returns {Array}
*/
console.time('快速排序')

function quickSort(arr, left, right) {
   let len = arr.length,
       partitionIndex;
   left = typeof left != 'number' ? 0 : left;
   right = typeof right != 'number' ? len - 1 : right;
   if (left < right) {
       partitionIndex = partition(arr, left, right);
       quickSort(arr, left, partitionIndex - 1);
       quickSort(arr, partitionIndex + 1, right);

   }
   return arr;
}

function partition(arr, left, right) {
   let pivot = left,
       index = pivot + 1;
   for (let i = index; i <= right; i++) {
       if (arr[i] < arr[pivot]) {
           swap(arr, i, index);
           index++;
       }
   }
   swap(arr, pivot, index - 1);
   return index - 1
}

function swap(arr, i, j) {
   let temp = arr[i];
   arr[i] = arr[j];
   arr[j] = temp;
}

let arr = [1, 2, 234, 235, 23452, 234525, 4, 2, 5]
console.log(quickSort(arr))
console.timeEnd('快速排序')

七、堆排序

/**
 * 堆排序
 * @param {Array} arr
 * @returns {Array}
 */

console.time('堆排序')
var len; //因为声明的多个函数都需要数据长度，所以把len设置成为全局变量

function buildMaxHeap(arr) { //建立大顶堆
    len = arr.length;
    for (var i = Math.floor(len / 2); i >= 0; i--) {
        heapify(arr, i);
    }
    return arr
}

function heapify(arr, i) { //堆调整
    var left = 2 * i + 1,
        right = 2 * i + 2,
        largest = i;

    if (left < len && arr[left] > arr[largest]) {
        largest = left;
    }

    if (right < len && arr[right] > arr[largest]) {
        largest = right;
    }

    if (largest != i) {
        swap(arr, i, largest);
        heapify(arr, largest);
    }
}

function swap(arr, i, j) {
    var temp = arr[i];
    arr[i] = arr[j];
    arr[j] = temp;
}

function heapSort(arr) {
    buildMaxHeap(arr);

    for (var i = arr.length - 1; i > 0; i--) {
        swap(arr, 0, i);
        len--;
        heapify(arr, 0);
    }
    return arr;
}

let arr = [1, 2, 234, 235, 23452, 234525, 4, 2, 5]
console.log(buildMaxHeap(arr))
console.timeEnd('堆排序')

八、计数排序

/**
 * 计数排序
 * @param {Array} arr
 * @returns {Array}
 */

console.time('计数排序')

function countingSort(arr, maxValue) {
    var bucket = new Array(maxValue + 1),
        sortedIndex = 0;
    arrLen = arr.length,
        bucketLen = maxValue + 1;

    for (var i = 0; i < arrLen; i++) {
        if (!bucket[arr[i]]) {
            bucket[arr[i]] = 0;
        }
        bucket[arr[i]]++;
    }

    for (var j = 0; j < bucketLen; j++) {
        while (bucket[j] > 0) {
            arr[sortedIndex++] = j;
            bucket[j]--;
        }
    }

    return arr;
}

let arr = [1, 2, 234, 235, 23452, 234525, 4, 2, 5]
console.log(countingSort(arr))
console.timeEnd('计数排序')

九、桶排序

/**
 * 桶排序
 * @param {Array} arr
 * @returns {Array}
 */

console.time('桶排序')

function bucketSort(arr, bucketSize) {
    if (arr.length === 0) {
        return arr;
    }

    var i;
    var minValue = arr[0];
    var maxValue = arr[0];
    for (i = 1; i < arr.length; i++) {
        if (arr[i] < minValue) {
            minValue = arr[i]; //输入数据的最小值
        } else if (arr[i] > maxValue) {
            maxValue = arr[i]; //输入数据的最大值
        }
    }

    //桶的初始化
    var DEFAULT_BUCKET_SIZE = 5; //设置桶的默认数量为5
    bucketSize = bucketSize || DEFAULT_BUCKET_SIZE;
    var bucketCount = Math.floor((maxValue - minValue) / bucketSize) + 1;
    var buckets = new Array(bucketCount);
    for (i = 0; i < buckets.length; i++) {
        buckets[i] = [];
    }

    //利用映射函数将数据分配到各个桶中
    for (i = 0; i < arr.length; i++) {
        buckets[Math.floor((arr[i] - minValue) / bucketSize)].push(arr[i]);
    }

    arr.length = 0;
    for (i = 0; i < buckets.length; i++) {
        insertionSort(buckets[i]); //对每个桶进行排序，这里使用了插入排序
        for (var j = 0; j < buckets[i].length; j++) {
            arr.push(buckets[i][j]);
        }
    }

    return arr;
}
let arr = [1, 2, 234, 235, 23452, 234525, 4, 2, 5]
console.log(bucketSort(arr))
console.timeEnd('桶排序')

十、基数排序

/**
 * 基数排序
 * @param {Array} arr
 * @returns {Array}
 */

console.time('基数排序')

//LSD Radix Sort
var counter = [];

function radixSort(arr, maxDigit) {
    var mod = 10;
    var dev = 1;
    for (var i = 0; i < maxDigit; i++, dev *= 10, mod *= 10) {
        for (var j = 0; j < arr.length; j++) {
            var bucket = parseInt((arr[j] % mod) / dev);
            if (counter[bucket] == null) {
                counter[bucket] = [];
            }
            counter[bucket].push(arr[j]);
        }
        var pos = 0;
        for (var j = 0; j < counter.length; j++) {
            var value = null;
            if (counter[j] != null) {
                while ((value = counter[j].shift()) != null) {
                    arr[pos++] = value;
                }
            }
        }
    }
    return arr;
}

let arr = [1, 2, 234, 235, 23452, 234525, 4, 2, 5]
console.log(radixSort(arr))
console.timeEnd('基数排序')