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  • STL 源代码剖析 算法 stl_algo.h -- merge sort

    本文为senlie原创。转载请保留此地址:http://blog.csdn.net/zhengsenlie


    merge sort

    ----------------------------------------------------------------------



    描写叙述:归并排序
    思路:
    1.将区间对半切割
    2.对左、右段分别排序
    3.利用inplace_merge将左、右段合并成为一个完整的有序序列


    复杂度:O(nlog n)
    源代码:
    template<class BidirectionalIter>
    void mergesort(BidirectionalIter first, BidirectionalIter last){
    	typename iterator_traits<BidirectionalIter>::diference_type n = distance(first,last);
    	if(n == 0 || n == 1) return ;
    	else{
    		BidirectionalIter mid = first + n / 2;
    		mergesort(first, mid);
    		mergesort(mid, last);
    		inplace_merge(first, mid, last);
    	}
    }


    演示样例:

    int main()
    {
    
    	int a[]={3,8,0,6,7,4,2,1,9,3,1,8,3,9,2,0,9};
    	int *a_end=a+sizeof a/sizeof(int);
    	
    
    	std::cout<<"a before mergesort: ";
    	std::for_each(a, a_end, print<int>);
    	std::cout<<'
    ';
    
    	mergesort(a, a_end);
    
    	std::cout<<"a after mergesort: ";
    	std::for_each(a, a_end, print<int>);
    	std::cout<<'
    ';
    
    	return 0;
    }


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  • 原文地址:https://www.cnblogs.com/yxwkf/p/5208147.html
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