C++ Algorithm rotate_copy()用法及代碼示例

C++ 算法 rotate_copy() 函數用於對 [first, last) 範圍內的元素進行旋轉複製。

序列將從源序列中間的元素開始，最後一個元素將在第一個元素之後。
它將第一個和中間的元素附加到中間和最後一個元素之間的元素。

用法

template <class ForwardIterator, class OutputIterator>
OutputIterator rotate_copy (ForwardIterator first, ForwardIterator middle,
ForwardIterator last, OutputIterator result);

參數

first:一個前向迭代器，指向要旋轉的範圍內第一個元素的位置。

middle: 向前迭代器尋址範圍 [first, last) 中移動到範圍中第一個位置的元素。

last:一個向前迭代器，指向元素被反轉的範圍內最後一個元素的位置。

result:一個輸出迭代器，指向目標範圍中第一個元素的位置。

返回值

rotate_copy() 函數返回一個輸出迭代器尋址到複製範圍的末尾。

複雜度

複雜度在 [first, last)：為每個元素執行賦值。

數據競爭

訪問範圍 [first, last) 中的對象。

結果和返回值之間範圍內的對象發生了變化。

異常

如果元素賦值或迭代器上的操作引發異常，則此函數將引發異常。

注意：無效的參數會導致未定義的行為。

例子1

讓我們看看旋轉給定字符串的簡單示例：

#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;
}

輸出：

Before Rotate: N I K I T A
After Rotate  : I K I T A N

例子2

讓我們看另一個簡單的例子：

#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;
}

輸出：

3 4 5 1 2

例子3

讓我們看另一個簡單的例子：

#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;
}

輸出：

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

讓我們看另一個簡單的例子：

#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;
}

輸出：

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

相關用法

注：本文由純淨天空篩選整理自 C++ Algorithm rotate_copy()。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。