C++/STL Algorithms Helper/partial sum
Содержание
- 1 make a sequence starting at -10 and increasing by 100 and sum it with partial_sum
- 2 Making Consecutive Numbers
- 3 partial_sum( ) creates a sequence that is a running total of the original sequence.
- 4 Use partial_sum to convert elements in a container into absolute values
- 5 Use partial_sum to print all partial products
- 6 Use partial_sum to print all partial sums
make a sequence starting at -10 and increasing by 100 and sum it with partial_sum
#include <algorithm>
#include <functional>
#include <iomanip>
#include <numeric>
#include <string>
#include <vector>
#include <iostream>
using namespace std;
template <class T>
void print(T& c){
for( typename T::iterator i = c.begin(); i != c.end(); i++ ){
std::cout << *i << endl;
}
}
bool in_string( char c, const string target ){
return target.find( c ) != string::npos;
}
int main( ){
vector<float> v( 5, 1 );
// make a sequence starting at -10 and increasing by 100
v.assign( v.size(), 100 );
v[0] = -10;
partial_sum( v.begin(), v.end(), v.begin() );
print( v );
}
Making Consecutive Numbers
#include <iostream>
#include <numeric>
#include <vector>
using namespace std;
template <class T>
void print(T& c){
for( typename T::iterator i = c.begin(); i != c.end(); i++ ){
std::cout << *i << endl;
}
}
int main( )
{
vector<int> num1( 5, 1 );
partial_sum( num1.begin(), num1.end(), num1.begin() );
print( num1 );
// intervals of 1 starting at 4
num1.assign( num1.size(), 1 );
num1[0] = 4;
partial_sum( num1.begin(), num1.end(), num1.begin() );
print( num1 );
}
partial_sum( ) creates a sequence that is a running total of the original sequence.
#include <iostream>
#include <vector>
#include <numeric>
using namespace std;
int main()
{
vector<int> v(5), r(5);
int i;
for(i=0; i<5; i++) v[i] = i;
for(i=0; i<5; i++)
cout << v[i] << endl;
partial_sum(v.begin(), v.end(), r.begin());
for(i=0; i<5; i++)
cout << r[i] << endl;
return 0;
}
Use partial_sum to convert elements in a container into absolute values
/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>
/* PRINT_ELEMENTS()
* - prints optional C-string optcstr followed by
* - all elements of the collection coll
* - separated by spaces
*/
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
typename T::const_iterator pos;
std::cout << optcstr;
for (pos=coll.begin(); pos!=coll.end(); ++pos) {
std::cout << *pos << " ";
}
std::cout << std::endl;
}
/* INSERT_ELEMENTS (collection, first, last)
* - fill values from first to last into the collection
* - NOTE: NO half-open range
*/
template <class T>
inline void INSERT_ELEMENTS (T& coll, int first, int last)
{
for (int i=first; i<=last; ++i) {
coll.insert(coll.end(),i);
}
}
using namespace std;
int main()
{
vector<int> coll;
coll.push_back(17);
coll.push_back(-3);
coll.push_back(22);
coll.push_back(13);
coll.push_back(13);
coll.push_back(-9);
PRINT_ELEMENTS(coll,"coll: ");
// convert into absolute values
partial_sum (coll.begin(), coll.end(), // source
coll.begin()); // destination
PRINT_ELEMENTS(coll,"absolute: ");
}
/*
coll: 17 -3 22 13 13 -9
absolute: 17 14 36 49 62 53
*/
Use partial_sum to print all partial products
/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>
/* PRINT_ELEMENTS()
* - prints optional C-string optcstr followed by
* - all elements of the collection coll
* - separated by spaces
*/
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
typename T::const_iterator pos;
std::cout << optcstr;
for (pos=coll.begin(); pos!=coll.end(); ++pos) {
std::cout << *pos << " ";
}
std::cout << std::endl;
}
/* INSERT_ELEMENTS (collection, first, last)
* - fill values from first to last into the collection
* - NOTE: NO half-open range
*/
template <class T>
inline void INSERT_ELEMENTS (T& coll, int first, int last)
{
for (int i=first; i<=last; ++i) {
coll.insert(coll.end(),i);
}
}
using namespace std;
int main()
{
vector<int> coll;
INSERT_ELEMENTS(coll,1,6);
PRINT_ELEMENTS(coll);
// print all partial products
partial_sum (coll.begin(), coll.end(), // source range
ostream_iterator<int>(cout," "), // destination
multiplies<int>()); // operation
cout << endl;
}
/*
1 2 3 4 5 6
1 2 6 24 120 720
*/
Use partial_sum to print all partial sums
/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>
/* PRINT_ELEMENTS()
* - prints optional C-string optcstr followed by
* - all elements of the collection coll
* - separated by spaces
*/
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
typename T::const_iterator pos;
std::cout << optcstr;
for (pos=coll.begin(); pos!=coll.end(); ++pos) {
std::cout << *pos << " ";
}
std::cout << std::endl;
}
/* INSERT_ELEMENTS (collection, first, last)
* - fill values from first to last into the collection
* - NOTE: NO half-open range
*/
template <class T>
inline void INSERT_ELEMENTS (T& coll, int first, int last)
{
for (int i=first; i<=last; ++i) {
coll.insert(coll.end(),i);
}
}
using namespace std;
int main()
{
vector<int> coll;
INSERT_ELEMENTS(coll,1,6);
PRINT_ELEMENTS(coll);
// print all partial sums
partial_sum (coll.begin(), coll.end(), // source range
ostream_iterator<int>(cout," ")); // destination
cout << endl;
}
/*
1 2 3 4 5 6
1 3 6 10 15 21
*/