STLalgorithm算法next_permutation,prev_permutation(39)
next_permutation原型:
std::next_permutation
default (1) |
template <class BidirectionalIterator>
bool next_permutation (BidirectionalIterator first,
BidirectionalIterator last);
|
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custom (2) |
template <class BidirectionalIterator, class Compare>
bool next_permutation (BidirectionalIterator first,
BidirectionalIterator last, Compare comp);
|
该函数是返回范围序列内元素的下一个更大的(根据字典序进行比较)排列。并将该排列存放到该范围内。
如果成功则返回true,如果当前范围的序列已经是最大的了,则返回false.
一个简单的例子:
#include <iostream> #include <algorithm> #include <vector> using namespace std; void nextpermutation(){ vector<int> vi{1,3,2}; cout<<"at first vi="; for(int i:vi) cout<<i<<" "; cout<<endl; cout<<"next_permutation(vi.begin(),vi.end())"<<endl; while(next_permutation(vi.begin(),vi.end())){ for(int i:vi) cout<<i<<" "; cout<<endl; } cout<<"all greater permutation show on!"<<endl; }
运行截图:
pre_permutation原型:
std::prev_permutation
default (1) |
template <class BidirectionalIterator> bool prev_permutation (BidirectionalIterator first, BidirectionalIterator last ); |
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custom (2) |
template <class BidirectionalIterator, class Compare> bool prev_permutation (BidirectionalIterator first, BidirectionalIterator last, Compare comp); |
该函数和next_permutation刚好相反,是返回一个更小的排列。
返回值也是true或者false,规则也是一样。
一个简单的例子:
#include <iostream> #include <algorithm> #include <vector> using namespace std; void prevpermutation(){ vector<int> vi{2,3,1}; cout<<"at first vi="; for(int i:vi) cout<<i<<" "; cout<<endl; cout<<"pre_permutation(vi.begin(),vi.end())"<<endl; while(prev_permutation(vi.begin(),vi.end())){ for(int i:vi) cout<<i<<" "; cout<<endl; } cout<<"all smaller permutation show on!"<<endl; }
运行截图:
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author:天下无双
Email:coderguang@gmail.com
2014-9-19
于GDUT
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