STLalgorithm算法rotate,rotate_copy(51)
rotate原型:
std::rotate
该函数是循环移位函数。
效果是交换[middle,last)和[first,middle)部分的位置。
具体实现请自行搜索。
类似实现为:
template <class ForwardIterator> void rotate (ForwardIterator first, ForwardIterator middle, ForwardIterator last) { ForwardIterator next = middle; while (first!=next) { swap (*first++,*next++); if (next==last) next=middle; else if (first==middle) middle=next; } }
一个简单的例子:
#include <iostream> #include <algorithm> #include <vector> using namespace std; void mrotate() { vector<int> vi{1,2,3,4,5,6}; vector<int> vresult{10,20,30,40,50}; cout<<"vi="; for(int i:vi) cout<<i<<" "; cout<<endl; cout<<"vresult="; for(int i:vresult) cout<<i<<" "; cout<<endl; rotate(vi.begin(),vi.begin()+3,vi.end()); rotate(vresult.begin(),vresult.end()-1,vresult.end()); cout<<"after rotate(vi.begin(),vi.begin()+3,vi.end())"<<endl; cout<<"vi="; for(int i:vi) cout<<i<<" "; cout<<endl; cout<<"after rotate(vresult.begin(),vresult.end()-1,vresult.end());"<<endl; cout<<"vresult="; for(int i:vresult) cout<<i<<" "; cout<<endl; }
运行截图:
rotate_copy原型:
std::rotate_copy
template <class ForwardIterator, class OutputIterator> OutputIterator rotate_copy (ForwardIterator first, ForwardIterator middle, ForwardIterator last, OutputIterator result);
该函数是将rotate后的序列存放到result开始的位置。
实现类似于:
template <class ForwardIterator, class OutputIterator> OutputIterator rotate_copy (ForwardIterator first, ForwardIterator middle, ForwardIterator last, OutputIterator result) { result=std::copy (middle,last,result); return std::copy (first,middle,result); }
一个简单的例子:
#include <iostream> #include <algorithm> #include <vector> using namespace std; void mrotatecopy() { vector<int> vi{1,2,3,4,5,6}; vector<int> vresult(6); cout<<"vi="; for(int i:vi) cout<<i<<" "; cout<<endl; cout<<"vresult="; for(int i:vresult) cout<<i<<" "; cout<<endl; rotate_copy(vi.begin(),vi.begin()+3,vi.end(),vresult.begin()); cout<<"after rotate_copy(vi.begin(),vi.begin()+3,vi.end(),vresult.begin())"<<endl; cout<<"vi="; for(int i:vi) cout<<i<<" "; cout<<endl; cout<<"vresult="; for(int i:vresult) cout<<i<<" "; cout<<endl; }
运行截图:
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author:天下无双
Email:coderguang@gmail.com
2014-9-26
于GDUT
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