STL常用算法: fill,rotate,rotate_copy.

fill算法用来填充容器，当然创建容器的时候，也可以达到与fill算法一样的效果.

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
//fill算法的手动实现.
template <typename T, typename V>
void myFill(T first, T last, const V value)
{while (first != last){*first++ = value;}
}int main()
{vector<int> s = {
   1,2,3,4,5,6,7};//用来让指定范围内的元素填充为5.fill(s.begin(), s.begin() + 3, 5);  // 5 5 5 4 5 6 7//当然这样也是可以的.给容器temp填充了10个5.vector<int> temp(10,5);system("pause");return 0;
}

rotate用来循环容器内的元素.但它和swap_ranges不同，它旋转的元素个数不用相等.

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;//rotate的实现.
template <typename T>
void myRotate(T first, T mid, T last)
{//这个实现挺有趣的,倒序即可实现.reverse(first, mid);reverse(mid, last);reverse(first, last);
}
int main()
{vector<int> s = {
   1,2,3,4,5,6,7};rotate(s.begin(), s.begin() + 3, s.end());  // 4 5 6 7 1 2 3system("pause");return 0;
}

既然有rotate,那么肯定有rotate_copy了.

template <typename T>
void myRotate_copy(T first, T mid, T last, T new_first)
{//一般有copy的算法，都比较简单实现.T temp = mid;while (temp != last){*new_first = *temp++;}while (first != mid){*new_first = *first++;}
}