# Benjamin

## STL算法(Algorithms):极值

1、min：返回两个两个参数中的最小值

template <class T, class Compare>
const T& min ( const T& a, const T& b, Compare comp );

// min example
#include <iostream>
#include <algorithm>
using namespace std;

int main () {
cout << "min(1,2)==" << min(1,2) << endl;
cout << "min(2,1)==" << min(2,1) << endl;
cout << "min('a','z')==" << min('a','z') << endl;
cout << "min(3.14,2.72)==" << min(3.14,2.72) << endl;
return 0;
}
2、max：返回两个参数中的大值

template <class T> const T& max ( const T& a, const T& b );
template <class T, class Compare>
const T& max ( const T& a, const T& b, Compare comp );

// max example
#include <iostream>
#include <algorithm>
using namespace std;

int main () { cout << "max(1,2)==" << max(1,2) << endl;
cout << "max(2,1)==" << max(2,1) << endl;
cout << "max('a','z')==" << max('a','z') << endl;
cout << "max(3.14,2.73)==" << max(3.14,2.73) << endl;
return 0;
}
3、min_element：返回(迭代器)指定范围内的最小元素

// min_element/max_element
#include <iostream>
#include <algorithm>
using namespace std;

bool myfn(int i, int j) { return i<j; }

struct myclass {
bool operator() (int i,int j) { return i<j; }
} myobj;

int main () {
int myints[] = {3,7,2,5,6,4,9};

// using default comparison:
cout << "The smallest element is " << *min_element(myints,myints+7) << endl;
cout << "The largest element is " << *max_element(myints,myints+7) << endl;

// using function myfn as comp:
cout << "The smallest element is " << *min_element(myints,myints+7,myfn) << endl;
cout << "The largest element is " << *max_element(myints,myints+7,myfn) << endl;

// using object myobj as comp:
cout << "The smallest element is " << *min_element(myints,myints+7,myobj) << endl; cout << "The largest element is " << *max_element(myints,myints+7,myobj) << endl;

return 0;
}
4、max_element：返回(迭代器)指定范围内的最小元素

template <class ForwardIterator>
ForwardIterator max_element ( ForwardIterator first, ForwardIterator last );

template <class ForwardIterator, class Compare>
ForwardIterator max_element ( ForwardIterator first, ForwardIterator last,
Compare comp );

// min_element/max_element
#include <iostream>
#include <algorithm>
using namespace std;

bool myfn(int i, int j) { return i<j; }

struct myclass {
bool operator() (int i,int j) { return i<j; }
} myobj;

int main () {
int myints[] = {3,7,2,5,6,4,9};

// using default comparison:
cout << "The smallest element is " << *min_element(myints,myints+7) << endl;
cout << "The largest element is " << *max_element(myints,myints+7) << endl;

// using function myfn as comp:
cout << "The smallest element is " << *min_element(myints,myints+7,myfn) << endl;
cout << "The largest element is " << *max_element(myints,myints+7,myfn) << endl;

// using object myobj as comp:
cout << "The smallest element is " << *min_element(myints,myints+7,myobj) << endl; cout << "The largest element is " << *max_element(myints,myints+7,myobj) << endl;

return 0;
}
5、next_permutation：返回的是(序列中所有元素组合中的)一个

template <class BidirectionalIterator>
bool next_permutation (BidirectionalIterator first,
BidirectionalIterator last );

template <class BidirectionalIterator, class Compare>
bool next_permutation (BidirectionalIterator first,
BidirectionalIterator last, Compare comp);

```// next_permutation
#include <iostream>
#include <algorithm>
using namespace std;

int main () {
int myints[] = {1,2,3};

cout << "The 3! possible permutations with 3 elements:\n";

sort (myints,myints+3);

do {
cout << myints[0] << " " << myints[1] << " " << myints[2] << endl;
} while ( next_permutation (myints,myints+3) );

return 0;
}6、prev_permutation：和next_permutation功能类似，返回的是序列中(所有元素)前一个组合原型：<algorithm>template <class BidirectionalIterator>
bool prev_permutation (BidirectionalIterator first,
BidirectionalIterator last );

template <class BidirectionalIterator, class Compare>
bool prev_permutation (BidirectionalIterator first,
BidirectionalIterator last, Compare comp);```
`示例：`
```// prev_permutation
#include <iostream>
#include <algorithm>
using namespace std;

int main () {
int myints[] = {1,2,3};

cout << "The 3! possible permutations with 3 elements:\n";

sort (myints,myints+3);
reverse (myints,myints+3);

do {
cout << myints[0] << " " << myints[1] << " " << myints[2] << endl;
} while ( prev_permutation (myints,myints+3) );

return 0;
}7、lexicographical_compare：字典比较(针对的是两个序列，返回的是布尔值)原型：template <class InputIterator1, class InputIterator2>bool lexicographical_compare ( InputIterator1 first1, InputIterator1 last1,```
`                                 InputIterator2 first2, InputIterator2 last2 );`
`template <class InputIterator1, class InputIterator2, class Compare>`
`  bool lexicographical_compare ( InputIterator1 first1, InputIterator1 last1,`
`                                 InputIterator2 first2, InputIterator2 last2,`
```                                 Compare comp );示例：// lexicographical_compare example
#include <iostream>
#include <algorithm>
#include <cctype>
using namespace std;

// a case-insensitive comparison function:
bool mycomp (char c1, char c2)

int main () {
char first[]="Apple";         // 5 letters
char second[]="apartment";    // 9 letters

cout << "Using default comparison (operator<): ";
if (lexicographical_compare(first,first+5,second,second+9))
cout << first << " is less than " << second << endl;
else
if (lexicographical_compare(second,second+9,first,first+5))
cout << first << " is greater than " << second << endl;
else
cout << first << " and " << second << " are equivalent\n";

cout << "Using mycomp as comparison object: ";
if (lexicographical_compare(first,first+5,second,second+9,mycomp))
cout << first << " is less than " << second << endl;
else
if (lexicographical_compare(second,second+9,first,first+5,mycomp))
cout << first << " is greater than " << second << endl;
else
cout << first << " and " << second << " are equivalent\n";

return 0;
}```
`` ``

posted on 2012-01-08 16:54 Benjamin 阅读(669) 评论(1)  编辑 收藏 引用 所属分类: 泛型编程

## #re: STL算法(Algorithms):极值[未登录]回复更多评论

2012-01-09 13:26 | 春秋十二月