http://www.cnblogs.com/BeyondAnyTime/archive/2012/05/27/2520532.html
一、非变异算法
是一组不破坏操作数据的模板函数,用来对序列数据进行逐个处理、元素查找、子序列搜索、统计和匹配。非变异算法具有极为广泛的适用性,基本上可应用与各种容器。
1. 查找容器元素 - find
函数功能:
它用于查找等于某值的元素。它在迭代器区间[first,last)(闭开区间)上查找等于value值的元素,如果迭代器i所指的元素满足*i=value,则返回迭代器i;未找到满足条件的元素,返回last。
函数原型:
#include <algorithm> template <class InputIterator, class T> InputIterator find (InputIterator first, InputIterator last, const T& val);
输入参数:
first, last
输入查询序列的开始和结束位置,注意:这两个参数为迭代器。
val
要查询的值
返回值:
返回查询结果的迭代器
实例:
#include <vector> #include <algorithm> #include <iostream> using namespace std; void main() { //为vecIntegers添加数据 vector<int> vecIntegers; for (int nNum=0; nNum<10;++nNum) { vecIntegers.push_back(nNum); } //打印数据 vector<int>::const_iterator iElementLocator; for (iElementLocator=vecIntegers.begin(); iElementLocator != vecIntegers.end(); ++iElementLocator) { cout << *iElementLocator << ' '; } cout << endl; /*****************关键代码******************************/ //查找数字 3 //注意:返回值为迭代器 vector<int>::iterator iElementFound; iElementFound = find(vecIntegers.begin(), vecIntegers.end(), 3); if (iElementFound != vecIntegers.end()) //如果找到结果 { cout << *iElementFound << endl; } else { cout << "没有找到结果!" << endl; } /****************************************************/ }
0 1 2 3 4 5 6 7 8 9 3 Press any key to continue
2. 条件查找容器元素 - find_if
利用返回布尔值的谓词判断pred,检查迭代器区间[first,last)(闭开区间)上的每一个元素,如果迭代器i满足pred(*i)=true,表示找到元素并返回迭代值i(找到的第一个符合条件的元素);未找到元素,返回末位置last。
函数原型:find_if(v.begin(),v.end(),divby5);
#include <vector> #include <algorithm> #include <iostream> using namespace std; bool divby5(int x) { return x%5 ? 0:1; } void main() { vector<int> v(20); for (int i = 0; i < v.size(); i++) { v[i] = (i+1)*(i+3); cout << v[i] << ' '; } cout << endl; vector<int>::iterator ilocation; ilocation = find_if(v.begin(),v.end(),divby5); if(ilocation != v.end()) { cout << "找到第一个能被5整除的元素:" << *ilocation << endl << "元素的索引位置是: " << ilocation-v.begin() << endl; } }
3 8 15 24 35 48 63 80 99 120 143 168 195 224 255 288 323 360 399 440 找到第一个能被5整除的元素:15 元素的索引位置是:2 Press any key to continue
3. 统计等于某值的容器元素个数 - count
函数原型:
template<class InputIterator, class T> inline size_t count( InputIterator First, InputIterator Last, const T& Value )
#include <iostream> #include <algorithm> #include <functional> #include <string> #include <vector> void main() { using namespace std; const int VECTOR_SIZE = 8 ; // Define a template class vector of strings typedef vector<string > StringVector ; //Define an iterator for template class vector of strings typedef StringVector::iterator StringVectorIt ; StringVector NamesVect(VECTOR_SIZE) ; //vector containing names string value("Sea") ; // stores the value used // to count matching elements StringVectorIt start, end, it ; ptrdiff_t result = 0 ; // stores count of elements // that match value. // Initialize vector NamesVect NamesVect[0] = "She" ; NamesVect[1] = "Sells" ; NamesVect[2] = "Sea" ; NamesVect[3] = "Shells" ; NamesVect[4] = "by" ; NamesVect[5] = "the" ; NamesVect[6] = "Sea" ; NamesVect[7] = "Shore" ; start = NamesVect.begin() ; // location of first // element of NamesVect end = NamesVect.end() ; // one past the location // last element of NamesVect // print content of NamesVect cout << "NamesVect { " ; for(it = start; it != end; it++) { cout << *it << " " ; } cout << " }\n" << endl ; // Count the number of elements in the range [first, last +1) // that match value. result = count(start, end, value) ; // print the count of elements that match value cout << "Number of elements that match \"Sea\" = " << result << endl ; }
NamesVect {She Sells Sea Shells by the Sea Shore} Number of elements that match "Sea" = 2 Press any key to continue
4. 条件统计 - count_if
count_if(l.begin(),l.end(),pred)
谓词pred含义同find_if中的谓词。例子可以参考例2.
函数原型:
template<class _InIt, class _Pr> inline typename iterator_traits<_InIt>::difference_type count_if(_InIt _First, _InIt _Last, _Pr _Pred);
示例:
#include <iostream> #include <algorithm> #include <functional> #include <string> #include <vector> using namespace std; // Return true if string str starts with letter 'S' int MatchFirstChar( const string& str) { string s("S") ; return s == str.substr(0,1) ; } void main() { const int VECTOR_SIZE = 8 ; // Define a template class vector of strings typedef vector<string > StringVector ; //Define an iterator for template class vector of strings typedef StringVector::iterator StringVectorIt ; StringVector NamesVect(VECTOR_SIZE) ; //vector containing names StringVectorIt start, end, it ; ptrdiff_t result = 0 ; // stores count of elements // that match value. // Initialize vector NamesVect NamesVect[0] = "She" ; NamesVect[1] = "Sells" ; NamesVect[2] = "Sea" ; NamesVect[3] = "Shells" ; NamesVect[4] = "by" ; NamesVect[5] = "the" ; NamesVect[6] = "Sea" ; NamesVect[7] = "Shore" ; start = NamesVect.begin() ; // location of first // element of NamesVect end = NamesVect.end() ; // one past the location // last element of NamesVect // print content of NamesVect cout << "NamesVect { " ; for(it = start; it != end; it++) cout << *it << " " ; cout << " }\n" << endl ; // Count the number of elements in the range [first, last +1) // that start with letter 'S' result = count_if(start, end, MatchFirstChar) ; // print the count of elements that start with letter 'S' cout << "Number of elements that start with letter \"S\" = " << result << endl ; }
NamesVect {She Sells Sea Shells by the Sea Shore} Number of elements that start with letter "S" = 6 Press any key to continue
5. 子序列搜索 - search
search算法函数在一个序列中搜索与另一序列匹配的子序列。参数分别为一个序列的开始位置,结束位置和另一个序列的开始,结束位置。
函数原型:search(v1.begin(),v1.end(),v2.begin(),v2.end());
#include <vector> #include <algorithm> #include <iostream> using namespace std; void main() { vector<int> v1; cout << "v1:"; for (int i = 0; i < 5; i++) { v1.push_back(i+5); //注意:v1定义时没有给定大小,因此这里不能直接使用赋值语句。 cout<<v1[i]<<' '; } cout << endl; vector<int> v2; cout << "v2:"; for (int i = 0; i < 2; i++) { v2.push_back(i+7); cout << v2[i] << ' '; } cout << endl; vector<int>::iterator ilocation; ilocation = search(v1.begin(),v1.end(),v2.begin(),v2.end()); if (ilocation != v1.end()) { cout << "v2的元素包含在v1中,起始元素为" << "v1[" << ilocation-v1.begin() << ']' << endl; } else { cout << "v2的元素不包含在v1中" << endl; } }
v1: 5 6 7 8 9 v2: 7 8 v2的元素包含在v1中,起始元素为v1[2]
6重复元素子序列搜索search_n
search_n算法函数搜索序列中是否有一系列元素值均为某个给定值的子序列。
函数原型:search_n(v.begin(),v.end(),3,8),
在v中找到3个连续的元素8
#include <vector> #include <algorithm> #include <iostream> using namespace std; void main() { vector<int> v; v.push_back(1); v.push_back(8); v.push_back(8); v.push_back(8); v.push_back(6); v.push_back(6); v.push_back(8); vector<int>::iterator i; i = search_n(v.begin(),v.end(),3,8); if (i != v.end()) { cout<<"在v中找到3个连续的元素8"<<endl; } else { cout<<"在v中未找到3个连续的元素8"<<endl; } }
在v中找到3个连续的元素8
7最后一个子序列搜索find_end
函数原型find_end(v1.begin(),v1.end(),v2.begin(),v2.end());
在V1中要求的位置查找V2中要求的序列。
#include <vector> #include <algorithm> #include <iostream> using namespace std; void main() { vector<int> v1; v1.push_back(-5); v1.push_back(1); v1.push_back(2); v1.push_back(-6); v1.push_back(-8); v1.push_back(1); v1.push_back(2); v1.push_back(-11); vector<int> v2; v2.push_back(1); v2.push_back(2); vector<int>::iterator i; i = find_end(v1.begin(), v1.end(), v2.begin(), v2.end()); if (i != v1.end()) { cout << "v1中找到最后一个匹配v2的子序列,位置在" << "v1[" << i-v1.begin() << "]" << endl; } }
"v1中找到最后一个匹配v2的子序列,位置在v1[5]
二、变异算法
是一组能够修改容器元素数据的模板函数。copy(v.begin(),v.end(),l.begin());将v中的元素复制到l中。
1元素复制copy
#include <vector> #include <list> #include <algorithm> #include <iostream> using namespace std; void main() { vector<int> v; v.push_back(1); v.push_back(3); v.push_back(5); list<int> l; l.push_back(2); l.push_back(4); l.push_back(6); l.push_back(8); l.push_back(10); copy(v.begin(),v.end(),l.begin()); list<int>::iterator i; for(i=l.begin();i!=l.end();i++) cout<<*i<<' '; cout<<endl; }
2元素变换transform改变
函数原型:transform(v.begin(),v.end(),l.begin(),square);
也是复制,但是要按某种方案复制。
#include <vector> #include <list> #include <algorithm> #include <iostream> using namespace std; int square(int x) { return x*x; } void main() { vector<int> v; v.push_back(5); v.push_back(15); v.push_back(25); list<int> l(3); transform(v.begin(),v.end(),l.begin(),square); list<int>::iterator i; for(i=l.begin();i!=l.end();i++) cout<<*i<<' '; cout<<endl; }
3替换replace
replace算法将指定元素值替换为新值。
#include <vector> #include <algorithm> #include <iostream> using namespace std; void main() { vector<int> v; v.push_back(13); v.push_back(25); v.push_back(27); v.push_back(25); v.push_back(29); replace(v.begin(),v.end(),25,100); vector<int>::iterator i; for(i=v.begin();i!=v.end();i++) cout<<*i<<' '; cout<<endl; }
13 100 27 100 29
4条件替换replace_if
函数原型:replace_if(v.begin(),v.end(),odd,100);
#include <vector> #include <algorithm> #include <iostream> using namespace std; bool odd(int x) { return x%2; } void main() { vector<int> v; for(int i=1;i<10;i++) v.push_back(i); replace_if(v.begin(),v.end(),odd,100); vector<int>::iterator ilocation; for(ilocation=v.begin();ilocation!=v.end();ilocation++) cout<<*ilocation<<' '; cout<<endl; }
5n次填充fill_n
函数原型fill_n(v.begin(),5,-1);向从v.begin开始的后面5个位置跳入-1
#include <vector> #include <algorithm> #include <iostream> using namespace std; void main() { vector<int> v(10); fill_n(v.begin(),5,-1); vector<int>::iterator ilocation; for(ilocation=v.begin();ilocation!=v.end();ilocation++) cout<<*ilocation<<' '; cout<<endl; } 输出结果:-1 -1 -1 -1 -1 0 0 0 0 0
6随机生成n个元素generate
函数原型:generate_n(v.begin(),5,rand);向从v.begin开始的后面5个位置随机填写数据。
#include <vector>
#include <algorithm>
#include <iostream>
using namespace std;
void main()
{
vector<int> v(10);
generate_n(v.begin(),5,rand);
vector<int>::iterator ilocation;
for(ilocation=v.begin();ilocation!=v.end();ilocation++)
cout<<*ilocation<<' ';
cout<<endl;
}
7条件移除remove_if
返回值相当于移除满足条件的元素后形成的新向量的end()值。
函数原型:remove_if(v.begin(),v.end(),even);
#include <vector>
#include <algorithm>
#include <iostream>
using namespace std;
bool even(int x)
{
return x%2?0:1;
}
void main()
{
vector<int> v;
for(int i=1;i<=10;i++)
v.push_back(i);
vector<int>::iterator ilocation,result;
cout<<"移除前:";
for(ilocation=v.begin();ilocation!=v.end();ilocation++)
cout<<*ilocation<<' ';
cout<<endl;
result=remove_if(v.begin(),v.end(),even);
cout<<"移除后:";
for(ilocation=v.begin();ilocation!=result;ilocation++)
cout<<*ilocation<<' ';
cout<<endl;
}
8剔除连续重复元素unique
函数原型:unique(v.begin(),v.end());
#include <vector>
#include <algorithm>
#include <iostream>
using namespace std;
void main()
{
vector<int> v;
v.push_back(2);
v.push_back(6);
v.push_back(6);
v.push_back(6);
v.push_back(9);
v.push_back(6);
v.push_back(3);
vector<int>::iterator ilocation,result;
result=unique(v.begin(),v.end());
for(ilocation=v.begin();ilocation!=result;ilocation++)
cout<<*ilocation<<' ';
cout<<endl;
}
输出结果:2 6 9 6 3
三、排序算法
1、创建堆make_heap
2、元素入堆push_heap(默认插入最后一个元素)
3、元素出堆pop_heap(与push_heap一样,pop_heap必须对堆操作才有意义)
#include <vector> #include <algorithm> #include <iostream> using namespace std; void main() { vector<int> v; v.push_back(5); v.push_back(6); v.push_back(4); v.push_back(8); v.push_back(2); v.push_back(3); v.push_back(7); v.push_back(1); v.push_back(9); make_heap(v.begin(), v.end()); v.push_back(20); push_heap(v.begin(), v.end()); vector<int>::iterator ilocation; for(ilocation = v.begin(); ilocation != v.end(); ilocation++) { cout << *ilocation << ' '; } cout << endl; pop_heap(v.begin(), v.end()); for (ilocation = v.begin(); ilocation != v.end(); ilocation++) { cout << *ilocation << ' '; } cout << endl; }
20 9 7 6 8 3 4 1 5 2 9 8 7 6 2 3 4 1 5 20
4. 堆排序 - sort_heap
使用:
make_heap(v.begin(),v.end()); sort_heap(v.begin(),v.end());
#include <vector> #include <algorithm> #include <iostream> using namespace std; void main() { vector<int> v; v.push_back(3); v.push_back(9); v.push_back(6); v.push_back(3); v.push_back(17); v.push_back(20); v.push_back(12); vector<int>::iterator ilocation; for (ilocation = v.begin(); ilocation != v.end(); ilocation++) { cout << *ilocation << ' '; } cout << endl; make_heap(v.begin(),v.end()); sort_heap(v.begin(),v.end()); for (ilocation = v.begin(); ilocation != v.end(); ilocation++) { cout << *ilocation << ' '; } cout << endl; }
3 9 6 3 17 20 12 3 3 6 9 12 17 20
5. 排序 - sort
sort详细解释参考link http://www.cppblog.com/mzty/archive/2005/12/15/1770.html
函数说明:
这个函数可以传两个参数或三个参数。第一个参数是要排序的区间首地址,第二个参数是区间 尾地址的下一地址。也就是说,排序的区间是[a,b)。简单来说,有一个数组int a[100],要对从a[0]到a[99]的元素进行排序,只要写sort(a,a+100)就行了,默认的排序方式是升序。
函数原型:
template<class RanIt> void sort(RanIt fist, RanIt last); template<class RanIt, class Pred> void sort(RanIt fist, RanIt last, Pred pr);
#include <vector> #include <algorithm> #include <iostream> using namespace std; void main() { vector<int> v; v.push_back(2); v.push_back(8); v.push_back(-15); v.push_back(90); v.push_back(26); v.push_back(7); v.push_back(23); v.push_back(30); v.push_back(-27); v.push_back(39); v.push_back(55); vector<int>::iterator ilocation; for (ilocation = v.begin(); ilocation != v.end(); ilocation++) { cout << *ilocation << ' '; } cout << endl; sort(v.begin(), v.end());//比较函数默认 for (ilocation = v.begin(); ilocation != v.end(); ilocation++) { cout << *ilocation << ' '; } cout << endl; }
2 8 -15 90 26 7 23 30 -27 39 55 -27 -15 2 7 8 23 26 30 39 55 90