C++ rotate_copy()
C++算法rotate_copy()
C++算法 rotate_copy()函数用于制作范围为[first，last的元素的旋转副本。 )。
序列将从源序列中间的元素开始，最后一个元素之后是第一个。
它将第一个元素和中间元素之间的元素附加到中间元素和最后一个元素之间的元素。
语法
template <class ForwardIterator, class OutputIterator>
OutputIterator rotate_copy (ForwardIterator first, ForwardIterator middle,
ForwardIterator last, OutputIterator result);
参数
first: 一个正向迭代器，指向要旋转范围内第一个元素的位置。
middle: 正向迭代器，它寻址到[first，last)范围内的元素，该元素已移至该范围内的第一位置。
last : 前向迭代器，在元素被反转的范围内，将位置指向最后一个元素之后的位置。
result: 指向目标范围中第一个元素位置的输出迭代器。
返回值
rotate_copy()函数返回一个输出迭代器，该输出迭代器的地址为复制范围的末尾。
复杂度
复杂度在范围内是线性的[first ，最后一个): 对每个元素进行分配。
数据竞争
访问[first，last)范围内的对象。
结果和返回值之间的范围内的对象已更改。
异常
如果分配了任何元素，则此函数将引发异常或对迭代器的操作会引发异常。
注意: 无效的参数会导致未定义的行为。
示例1
让我们看一下旋转给定字符串的简单示例:
#include <algorithm>
#include <iostream>
#include <string>
#include <iterator>
using namespace std;
int main() {
string str = " N I K I T A";
string result;
cout << "Before Rotate : "<< str << endl;
rotate_copy(str.begin(), str.begin() + 2, str.end(),
back_inserter(result));
cout <<"After Rotate : " << result << endl;
return 0;
}
输出:
Before Rotate : N I K I T A
After Rotate : I K I T A N
示例2
让我们看另一个简单的示例:
#include <algorithm>
#include <vector>
#include <iostream>
using namespace std;
int main()
{
vector<int> src = {1, 2, 3, 4, 5};
auto pivot = find(src.begin(), src.end(), 3);
vector<int> dest(src.size());
rotate_copy(src.begin(), pivot, src.end(), dest.begin());
for (const auto &i : dest) {
cout << i << ' ';
}
cout << '\n';
return 0;
}
输出:
示例3
让我们看另一个简单的示例:
#include <iostream>
#include <algorithm>
#include <vector>
#include <iomanip>
using namespace std;
void print(char a[], int N)
{
for(int i = 0; i < N; i++)
{
cout << (i + 1) << ". " << setw(1)
<< left << a[i] << " ";
}
cout << endl;
}
int main()
{
char s[] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H'};
int slen = sizeof(s) / sizeof(char), tlen = slen;
char t[tlen];
cout << "Character array s[] : ";
print(s, slen);
cout << "Rotate s[] with \'C\' as middle element and copy in t[]" << endl;
rotate_copy(s, s + 2, s + slen, t);
cout << "Character array t[] : ";
print(t, tlen);
cout << "Rotate t[] with \'A\' as middle element and copy in s[]" << endl;
rotate_copy(t, t + 6, t + tlen, s);
cout << "Character array s[] : ";
print(s, slen);
cout << "Character array t[] : ";
print(t, tlen);
return 0;
}
输出:
Character array s[] : 1. A 2. B 3. C 4. D 5. E 6. F 7. G 8. H
Rotate s[] with 'C' as middle element and copy in t[]
Character array t[] : 1. C 2. D 3. E 4. F 5. G 6. H 7. A 8. B
Rotate t[] with 'A' as middle element and copy in s[]
Character array s[] : 1. A 2. B 3. C 4. D 5. E 6. F 7. G 8. H
Character array t[] : 1. C 2. D 3. E 4. F 5. G 6. H 7. A 8. B
示例4
让我们看另一个简单的示例:
#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <functional>
using namespace std ;
int main()
{
const int VECTOR_SIZE = 8 ;
// Define a template class vector of strings
typedef vector<string> StrVector ;
//Define an iterator for template class vector of strings
typedef StrVector::iterator StrVectorIt ;
StrVector Tongue_Twister(VECTOR_SIZE) ;
StrVector Rotated_Twister(VECTOR_SIZE) ;
StrVectorIt start, middle, end, it, RTstart, RTend ;
start = Tongue_Twister.begin() ; // location of first
// element of Tongue_Twister
end = Tongue_Twister.end() ; // one past the location last
// element of Tongue_Twister
middle = start + 3 ; // start position for
// rotating elements
RTstart = Rotated_Twister.begin() ; // location of first
// element of Rotated_Twister
RTend = Rotated_Twister.end() ; // one past the location last
// element of Rotated_Twister
//Initialize vector Tongue_Twister
Tongue_Twister[0] = "she" ;
Tongue_Twister[1] = "sells" ;
Tongue_Twister[2] = "sea" ;
Tongue_Twister[3] = "shells" ;
Tongue_Twister[4] = "by";
Tongue_Twister[5] = "the";
Tongue_Twister[6] = "sea" ;
Tongue_Twister[7] = "shore" ;
cout << "Before calling rotate_copy:\n" << endl ;
// print content of Tongue_Twister
cout << "try this Tongue Twister: " ;
for(it = start; it != end; it++)
cout << *it << " " ;
cout << "\n\n" ;
// rotate the items in the vector Tongue_Twist to the right by
// 3 positions and copy the results to Rotated_Twister
rotate_copy(start, middle, end, RTstart) ;
cout << "After calling rotate_copy:\n" << endl ;
// print content of Tongue_Twister
cout << "Tongue_Twister: " ;
for(it = start; it != end; it++)
cout << *it << " " ;
cout << "\n\n" ;
// print content of Rotated_Twister
cout << "Now try the rotated Tongue Twister: " ;
for(it = RTstart; it != RTend; it++)
cout << *it << " " ;
cout << "\n\n" ;
return 0;
}
输出:
Before calling rotate_copy:
try this Tongue Twister: she sells sea shells by the sea shore
After calling rotate_copy:
Tongue_Twister: she sells sea shells by the sea shore
Now try the rotated Tongue Twister: shells by the sea shore she sells sea
