81 lines
2.2 KiB
C++
81 lines
2.2 KiB
C++
// Compile with -std=c++11
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#include<iostream>
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#include<vector>
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using namespace std;
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class pascal_triangle{
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vector<vector<int>> data; // This is the actual data
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void print_row(vector<int> dummy){
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for (vector<int>::iterator i = dummy.begin(); i != dummy.end(); ++i)
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cout<<*i<<" ";
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cout<<endl;
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}
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public:
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pascal_triangle(int dummy){ // Everything is done on the construction phase
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if (dummy > 0){ // if the argument is 0 or negative exit immediately
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vector<int> row;
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data.resize(dummy); // Theoretically this should work faster than consecutive push_back()s
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// The first row
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row.resize(1);
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row.at(0) = 1;
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data.at(0) = row;
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// The second row
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if (data.size() > 1){
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row.resize(2);
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row.at(0) = 1; row.at(1) = 1;
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data.at(1) = row;
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}
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// The other rows
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if (data.size() > 2){
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for (int i = 2; i < data.size(); i++){
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row.resize(i + 1); // Theoretically this should work faster than consecutive push_back()s
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row.front() = 1;
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for (int j = 1; j < row.size() - 1; j++)
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row.at(j) = data.at(i - 1).at(j - 1) + data.at(i - 1).at(j);
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row.back() = 1;
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data.at(i) = row;
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}
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}
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}
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}
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~pascal_triangle(){
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for (vector<vector<int>>::iterator i = data.begin(); i != data.end(); ++i)
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i->clear(); // I'm not sure about the necessity of this loop!
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data.clear();
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}
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void print_row(int dummy){
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if (dummy < data.size())
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for (vector<int>::iterator i = data.at(dummy).begin(); i != data.at(dummy).end(); ++i)
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cout<<*i<<" ";
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cout<<endl;
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}
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void print(){
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for (int i = 0; i < data.size(); i++)
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print_row(i);
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}
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int get_coeff(int dummy1, int dummy2){
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int result = 0;
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if ((dummy1 < data.size()) && (dummy2 < data.at(dummy1).size()))
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result = data.at(dummy1).at(dummy2);
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return result;
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}
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vector<int> get_row(int dummy){
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vector<int> result;
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if (dummy < data.size())
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result = data.at(dummy);
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return result;
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}
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};
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int main(){
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int n;
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cout<<endl<<"The Pascal's Triangle with a class!"<<endl<<endl<<"Enter the number of rows: ";
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cin>>n;
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pascal_triangle myptri(n);
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cout<<endl<<"The whole triangle:"<<endl;
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myptri.print();
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cout<<endl<<"Just one row:"<<endl;
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myptri.print_row(n/2);
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cout<<endl<<"Just one coefficient:"<<endl;
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cout<<myptri.get_coeff(n/2, n/4)<<endl<<endl;
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return 0;
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}
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