JavaScript 排序算法

基础构造函数

以下几种排序算法做为方法放在构造函数里。

function ArrayList () {
  var array = [];

  // 交换位置
  var swap = function (index1, index2) {
    var aux = array[index1];
    array[index1] = array[index2];
    array[index2] = aux;
  }

  this.insert = function (item) {
    array.push(item);
  };

  this.toString = function () {
    return array.join();
  };

  this.val = function () {
    return array;
  }

  // 冒泡排序
  this.bubbleSort = function () {
    //etc
  }
}

1. 冒泡排序

代码

this.bubbleSort = function () {
  console.time('Bubble Sort');
  var length = array.length;
  for (var i = 0; i < length; i++) {
    for (var j = 0; j < length - 1 - i; j++) {
      if (array[j] > array[j+1]) {
        swap(j, j + 1);
      }
    }
  }
  console.timeEnd('Bubble Sort');
}

图解

2. 选择排序

代码

this.selectionSort = function () {
  console.time('selectionSort');
  var length = array.length,
      indexMin;

  for (var i = 0; i < length - 1; i++) {
    indexMin = i;
    for (var j = i; j < length; j++) {
      if (array[indexMin] > array[j]) {
        indexMin = j;
      }
    }

    if (i !== indexMin) {
      swap(i, indexMin);
    }
  }
  console.timeEnd('selectionSort');
}

图解

3. 插入排序

代码

this.insertionSort = function () {
  console.time('insertionSort');
  var length = array.length,
      j, temp;

  for (var i = 1; i < length; i++) {
    j = i;
    temp = array[i];
    while (j > 0 && array[j-1] > temp) {
      array[j] = array[j-1];
      j--;
    }
    array[j] = temp;
  }
  console.timeEnd('insertionSort');
}

图解

4. 归并排序

代码

this.mergeSort = function () {
  console.time('mergeSort');
  array = mergeSortRec(array);
  console.timeEnd('mergeSort');
}
var mergeSortRec  = function (array) {
  var length = array.length;
  if (length === 1) {
    return array;
  }

  var mid = Math.floor(length / 2),
      left = array.slice(0, mid),
      right = array.slice(mid, length);

  return merge(mergeSortRec(left), mergeSortRec(right));
}
var merge = function (left, right) {
  var result = [],
      il = 0,
      ir = 0;

  while (il < left.length && ir < right.length) {
    if (left[il] < right[ir]) {
      result.push(left[il++]);
    } else {
      result.push(right[ir++]);
    }
  }

  while (il < left.length) {
    result.push(left[il++]);
  }

  while (ir < right.length) {
    result.push(right[ir++]);
  }

  return result;
}

图解

5. 快速排序

代码

this.quickSort = function () {
  console.time('quickSort');
  quick(array, 0, array.length - 1);
  console.timeEnd('quickSort');
}

var quick = function (array, left, right) {
  var index;
  if (array.length > 1) {
    index = partition(array, left, right);

    if (left < index - 1) {
      quick(array, left, index - 1);
    }

    if (index < right) {
      quick(array, index, right);
    }
  }
};

// 划分过程
var partition = function (array, left, right) {
  var pivot = array[Math.floor((right + left) / 2)],
      i = left,
      j = right;

  while (i < j) {
    while (array[i] < pivot) {
      i++;
    }

    while (array[j] > pivot) {
      j--;
    }

    if (i <= j) {
      swapQuickSort(array, i, j);
      i++;
      j--;
    }
  }
  return i;
}

var swapQuickSort = function (array, index1, index2) {
  var aux = array[index1];
  array[index1] = array[index2];
  array[index2] = aux;
}

图解

6. ECMAScript 排序

代码

this.esSort = function () {
  console.time('esSort');
  var tempArray = [];
  tempArray = array.sort(function (a, b) {
    return a - b;
  });
  console.timeEnd('esSort');
  return tempArray;
}

性能测试

环境

• OS：WIN10 64位

• 浏览器：Google Chrome 60.0.3112.78

代码

/**
* 创建随机数组
* @param  {[type]} size [description]
* @return {[type]}      [description]
*/
function createNonSortedArray (size) {
  var array = new ArrayList();
  for (var i = size; i > 0; i--) {
    var tempNum = Math.random() * i >>> 0;
    array.insert(tempNum);
  }
  return array;
}

// 冒泡排序
(function () {
  var array = createNonSortedArray(500);
  array.bubbleSort(); // Bubble Sort: 2.625ms
  console.log(array.val());
}());


// 选择排序
(function () {
  var array = createNonSortedArray(500);
  array.selectionSort(); // selectionSort: 1.986083984375ms
  console.log(array.val());
}());

// 插入排序
(function () {
  var array = createNonSortedArray(500);
  array.insertionSort(); // insertionSort: 1.825927734375ms
  console.log(array.val());
}());

// 归并排序
(function () {
  var array = createNonSortedArray(500);
  array.mergeSort(); // mergeSort: 0.76416015625ms
  console.log(array.val());
}());


// 快速排序
(function () {
  var array = createNonSortedArray(500);
  array.quickSort(); // quickSort: 0.39111328125ms
  console.log(array.val());
}());


// ES排序
(function () {
  var array = createNonSortedArray(500);
  array.esSort(); // esSort: 0.34130859375ms
  console.log(array.val());
}());

出处：http://blog.givebest.cn/javascript/2017/08/02/javascript-sorting-algorithms.html