Question

(Small Question) Recode apple.cpp(The following code)such that it uses suggested STL algorithms(in the comments) instead of hand-written loops

#include <iostream>
#include <ctime>
#include <cstdlib>
#include <vector>
#include <deque>
#include <string>

using std::cin; using std::cout; using std::endl;
using std::string;
using std::vector; using std::deque;

struct Apples{
double weight; // oz
string color; // red or green
void print() const { cout << color << ", " << weight << endl; }
};

int main(){
srand(time(nullptr));
const double minWeight = 8.;
const double maxWeight = 3.;
  
cout << "Input crate size: ";
int size;
cin >> size;
  
vector <Apples> crate(size);
  
// assign random weight and color to apples in the crate
// replace with generate()
for(auto it = crate.begin(); it != crate.end(); ++it){
it->weight = minWeight +
static_cast<double>(rand())/RAND_MAX*(maxWeight - minWeight);
it->color = rand() % 2 == 1 ? "green" : "red";
}
  
  
cout << "Enter weight to find: ";
double toFind;
cin >> toFind;
  
// count_if()
int cnt = 0;
for(auto it = crate.cbegin(); it != crate.cend(); ++it)
if(it->weight > toFind) ++cnt;
  
cout << "There are " << cnt << " apples heavier than "
<< toFind << " oz" << endl;
  
// find_if()
cout << "at positions ";
for(int i=0; i < size; ++i)
if(crate[i].weight > toFind)
cout << i << ", ";
cout << endl;
  
  
// max_element()
double heaviest = crate[0].weight;
for(int i=1; i < size; ++i)
if(crate[i].weight > heaviest) heaviest = crate[i].weight;
cout << "Heaviest apple weighs: " << heaviest << " oz" << endl;
  
  
// for_each() or accumulate()
double sum = 0;
for(int i=0; i < size; ++i)
sum += crate[i].weight;
cout << "Total apple weight is: " << sum << " oz" << endl;
  
  
// transform();
cout << "How much should they grow: ";
double toGrow;
cin >> toGrow;
for(int i=0; i < crate.size(); ++i)
crate[i].weight += toGrow;
  
// remove_if()
cout << "Input minimum acceptable weight: ";
double minAccept;
cin >> minAccept;
  
for(auto it=crate.begin(); it != crate.end(); )
if(it->weight < minAccept)
it = crate.erase(it);
else
++it;
  
cout << "removed " << size - crate.size() << " elements" << endl;
  
  
// bubble sort, replace with sort()
bool swapped;
do{
swapped = false;
for(int i=0; i < crate.size()-1; ++i)
if(crate[i].weight > crate[i+1].weight){
std::swap(crate[i], crate[i+1]);
swapped = true;
}
}while(swapped);
  
  
// moving all red apples from crate to peck
// remove_copy_if() with back_inserter()/front_inserter() or equivalents
deque<Apples> peck;
for(auto it=crate.begin(); it != crate.end();)
if(it->color == "red"){
peck.push_front(std::move(*it));
it=crate.erase(it);
}else
++it;
  
// for_each() possibly
cout << "apples in the create"<< endl;
for(const auto &e: crate) {
e.print();
}
  
cout << endl;
  
// for_each() possibly
cout << "apples in the peck"<< endl;
for(const auto &e: peck) {
e.print();
}
  
  
// prints every "space" apple in the peck
//
const int space=3;
cout << "\nevery " << space << "\'d apple in the peck"<< endl;
  
// replace with advance()/next()/distance()
// no iterator arithmetic
auto it=peck.cbegin(); int i = 0;
while(it != peck.cend()){
if(i == space){
it->print();
i=0;
}
++i;
++it;
}
  
  
// putting all small green apples in a jam
// use a binder to create a functor with configurable max weight
// accumulate() or count_if() then remove_if()
const double weightToJam = 10.0;
double jamWeight = 0;
for(auto it=crate.begin(); it != crate.end();)
if(it->weight < weightToJam){
jamWeight += it->weight;
it=crate.erase(it);
}else
++it;
  
cout << "Weight of jam is: " << jamWeight << endl;
  
}

Answer 1

Source Code

#include <iostream>
#include <ctime>
#include <cstdlib>
#include <vector>
#include <deque>
#include <string>

using std::cin; using std::cout; using std::endl;
using std::string;
using std::vector; using std::deque;

struct Apples{
double weight; // oz
string color; // red or green
void print() const { cout << color << ", " << weight << endl; }
};

int main(){
srand(time(nullptr));
const double minWeight = 8.;
const double maxWeight = 3.;
  
cout << "Input crate size: ";
int size;
cin >> size;
  
vector <Apples> crate(size);
  
// assign random weight and color to apples in the crate
// replace with generate()
for(auto it = crate.begin(); it != crate.end(); ++it){
it->weight = minWeight +
static_cast<double>(rand())/RAND_MAX*(maxWeight - minWeight);
it->color = rand() % 2 == 1 ? "green" : "red";
}
  
  
cout << "Enter weight to find: ";
double toFind;
cin >> toFind;
  
// count_if()
int cnt = 0;
for(auto it = crate.cbegin(); it != crate.cend(); ++it)
if(it->weight > toFind) ++cnt;
  
cout << "There are " << cnt << " apples heavier than "
<< toFind << " oz" << endl;
  
// find_if()
cout << "at positions ";
for(int i=0; i < size; ++i)
if(crate[i].weight > toFind)
cout << i << ", ";
cout << endl;
  
  
// max_element()
double heaviest = crate[0].weight;
for(int i=1; i < size; ++i)
if(crate[i].weight > heaviest) heaviest = crate[i].weight;
cout << "Heaviest apple weighs: " << heaviest << " oz" << endl;
  
  
// for_each() or accumulate()
double sum = 0;
for(int i=0; i < size; ++i)
sum += crate[i].weight;
cout << "Total apple weight is: " << sum << " oz" << endl;
  
  
// transform();
cout << "How much should they grow: ";
double toGrow;
cin >> toGrow;
for(int i=0; i < crate.size(); ++i)
crate[i].weight += toGrow;
  
// remove_if()
cout << "Input minimum acceptable weight: ";
double minAccept;
cin >> minAccept;
  
for(auto it=crate.begin(); it != crate.end(); )
if(it->weight < minAccept)
it = crate.erase(it);
else
++it;
  
cout << "removed " << size - crate.size() << " elements" << endl;
  
  
// bubble sort, replace with sort()
bool swapped;
do{
swapped = false;
for(int i=0; i < crate.size()-1; ++i)
if(crate[i].weight > crate[i+1].weight){
std::swap(crate[i], crate[i+1]);
swapped = true;
}
}while(swapped);
  
  
// moving all red apples from crate to peck
// remove_copy_if() with back_inserter()/front_inserter() or equivalents
deque<Apples> peck;
for(auto it=crate.begin(); it != crate.end();)
if(it->color == "red"){
peck.push_front(std::move(*it));
it=crate.erase(it);
}else
++it;
  
// for_each() possibly
cout << "apples in the create"<< endl;
for(const auto &e: crate) {
e.print();
}
  
cout << endl;
  
// for_each() possibly
cout << "apples in the peck"<< endl;
for(const auto &e: peck) {
e.print();
}
  
  
// prints every "space" apple in the peck
//
const int space=3;
cout << "\nevery " << space << "\'d apple in the peck"<< endl;
  
// replace with advance()/next()/distance()
// no iterator arithmetic
auto it=peck.cbegin(); int i = 0;
while(it != peck.cend()){
if(i == space){
it->print();
i=0;
}
++i;
++it;
}
  
  
// putting all small green apples in a jam
// use a binder to create a functor with configurable max weight
// accumulate() or count_if() then remove_if()
const double weightToJam = 10.0;
double jamWeight = 0;
for(auto it=crate.begin(); it != crate.end();)
if(it->weight < weightToJam){
jamWeight += it->weight;
it=crate.erase(it);
}else
++it;
  
cout << "Weight of jam is: " << jamWeight << endl;
  
}

The Output