整理下STL algorithms（4）
merge：
template <class InputIterator1, class InputIterator2, class OutputIterator>
OutputIterator merge ( InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2,
OutputIterator result );
template <class InputIterator1, class InputIterator2,
class OutputIterator, class Compare>
OutputIterator merge ( InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2,
OutputIterator result, Compare comp );
合并两个有序序列，添加到result中~~注意两个序列要都是有序的
相当于如下代码的工作：
与之相似的是inplace_merge:template <class InputIterator1, class InputIterator2, class OutputIterator>
OutputIterator merge ( InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2,
OutputIterator result )
{
while (true) {
*result++ = (*first2<*first1)? *first2++ : *first1++;
if (first1==last1) return copy(first2,last2,result);
if (first2==last2) return copy(first1,last1,result);
}
}
template <class BidirectionalIterator> void inplace_merge ( BidirectionalIterator first, BidirectionalIterator middle, BidirectionalIterator last ); template <class BidirectionalIterator, class Compare> void inplace_merge ( BidirectionalIterator first, BidirectionalIterator middle, BidirectionalIterator last, Compare comp );
inplace_merge合并一个中前后两段分别有序的序列，即[first,middle)与[middle,last)分别有序，合并这两个子序列，并把结果保存在[first,last）中。
includes:
template <class InputIterator1, class InputIterator2>
bool includes ( InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2 );
template <class InputIterator1, class InputIterator2, class Compare>
bool includes ( InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2, Compare comp );
测试[first2,last2)是否是[first1,last1)的子序列，注意这两个序列都是有序的~~set_union:
<algorithm>template <class InputIterator1, class InputIterator2, class OutputIterator> OutputIterator set_union ( InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, OutputIterator result ); template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare> OutputIterator set_union ( InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp );将两个有序序列去并集，将结果存放在result中，返回值是result的end~相应的取交集的算法是set_intersection:set_difference:// set_intersection example
#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
int main () {
int first[] = {5,10,15,20,25};
int second[] = {50,40,30,20,10};
vector<int> v(10); // 0 0 0 0 0 0 0 0 0 0
vector<int>::iterator it;
sort (first,first+5); // 5 10 15 20 25
sort (second,second+5); // 10 20 30 40 50
it=set_intersection (first, first+5, second, second+5, v.begin());
// 10 20 0 0 0 0 0 0 0 0
cout << "intersection has " << int(it - v.begin()) << " elements.\n";
return 0;
}
结果：intersection has 2 elements
template <class InputIterator1, class InputIterator2, class OutputIterator> OutputIterator set_difference ( InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, OutputIterator result ); template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare> OutputIterator set_difference ( InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp );
set_difference()算法计算两个集合[start1, end1)和[start2, end2)的差集, 并将差集存放到result.
两个集合以序列的形式给出, 且必须先按升序排好位置.
set_difference()是一个指向result序列末尾的迭代器.
template <class InputIterator1, class InputIterator2, class OutputIterator> OutputIterator set_symmetric_difference ( InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, OutputIterator result ); template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare> OutputIterator set_symmetric_difference ( InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp );
set_symmetric_difference()算法计算两个集合[start1, end1)和[start2, end2)的对称差, 并将差集储存到result中.
两个集合以序列形式给出, 而且必须按升序排好位置.
set_symmetric_difference()的返回值为指向result末尾的迭代器.
make_heap:
template <class RandomAccessIterator> void make_heap ( RandomAccessIterator first, RandomAccessIterator last ); template <class RandomAccessIterator, class Compare> void make_heap ( RandomAccessIterator first, RandomAccessIterator last, Compare comp );函数make_heap()将给定的序列[start, end)转换成堆.
如果严格弱排序函数对象cmp被指定, 则在比较元素时应用此函数替代<操作符.
push_heap:
template <class RandomAccessIterator> void push_heap ( RandomAccessIterator first, RandomAccessIterator last ); template <class RandomAccessIterator, class Compare> void push_heap ( RandomAccessIterator first, RandomAccessIterator last, Compare comp );函数push_heap()将插入一个元素(被放置在end之前的最后一个元素)到堆中(定义在区间[start,''end-1)中).
pop_heap:
template <class RandomAccessIterator>
void pop_heap ( RandomAccessIterator first, RandomAccessIterator last );
template <class RandomAccessIterator, class Compare>
void pop_heap ( RandomAccessIterator first, RandomAccessIterator last,
Compare comp );
pop_heap:template <class RandomAccessIterator>
void pop_heap ( RandomAccessIterator first, RandomAccessIterator last );
template <class RandomAccessIterator, class Compare>
void pop_heap ( RandomAccessIterator first, RandomAccessIterator last,
Compare comp );
该算法将第一个元素（堆最大元素）放到last-1的位置，并对[first,last-1)之间的元素进行重新调整，成堆序列sort_heap:
template <class RandomAccessIterator>
void sort_heap ( RandomAccessIterator first, RandomAccessIterator last );
template <class RandomAccessIterator, class Compare>
void sort_heap ( RandomAccessIterator first, RandomAccessIterator last,
Compare comp );
将堆转换为有序队列~~另外还有几个：
lexicographical_compare 按字典顺序检查一个序列是否小于另外一个序列
min 返回两个元素间的较小者
max 返回两个元素间的较大者
max_element 返回序列中的最大者
min_element 返回序列中的最小者
next_permutation 依照字典顺序生成序列的下一个稍大的排列
prev_permutation 依照字典顺序生成序列的下一个稍小的排列
