合并排序

具体原理可看这里

javascript版本：

        function merge(left, right){
          var result = [];
          while (left.length > 0 && right.length > 0){
            if (left[0] < right[0]){
              result.push(left.shift());//把最小的最先取出，放到结果集中
            } else {
              result.push(right.shift());
            }
          } return result.concat(left).concat(right);//剩下的就是合并，这样就排好序了
        }
        function mergeSort(array){
          if (array.length == 1) {
            return array;
          }
          var middle = Math.floor(array.length / 2),//求出中点
          left = array.slice(0, middle),//分割数组
          right = array.slice(middle);
          return merge(mergeSort(left), mergeSort(right));//递归合并与排序
        }

ruby版本：

  def merge(left, right)
    final = []
    until left.empty? or right.empty?
      final << ( left.first < right.first ? left.shift : right.shift )
    end
    final + left + right
  end
  def mergeSort(array)
    return array if array.size < 2
    left = array.first(array.size/2)
    right = array.last(array.size - array.size/2)
    merge(mergeSort(left), mergeSort(right))
  end

//by 司徒正美 function merge(left, right){ var result = []; while (left.length > 0 && right.length > 0){ if (left[0] < right[0]){ result.push(left.shift());//把最小的最先取出，放到结果集中 } else { result.push(right.shift()); } } return result.concat(left).concat(right);//剩下的就是合并，这样就排好序了 } function mergeSort(array){ if (array.length == 1) { return array; } var middle = Math.floor(array.length / 2),//求出中点 left = array.slice(0, middle),//分割数组 right = array.slice(middle); return merge(mergeSort(left), mergeSort(right));//递归合并与排序 } var a = [49, 38 ,65 ,97 ,76, 13, 27] alert(mergeSort(a))

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