Pascal's Triangle Solutions in C++

// Source : https://oj.leetcode.com/problems/pascals-triangle/
// Author : Hao Chen
// Date   : 2014-06-18



#include <stdlib.h>
#include <vector>
#include <iostream>
using namespace std;

vector<vector<int> > generate(int numRows) 
{
    vector<vector<int> > pascalTriangle;
    for (int i=0; i<numRows; i++){
        vector<int> v;
        if (i==0){
            v.push_back(1);
        } else {
            v.push_back(1);
            for(int j=0; j<pascalTriangle[i-1].size()-1; j++){
                v.push_back(pascalTriangle[i-1][j] + pascalTriangle[i-1][j+1]);
            }
            v.push_back(1);
        }
        pascalTriangle.push_back(v); 
    }
    return pascalTriangle;
}

void printTriangle(vector< vector<int> > pt)
{
	cout << "[" << endl;
    for(int i=0; i<pt.size(); i++){
    	for(int space=(pt.size()-i-1); space>=0; space--){
    		cout << " ";
    	}
        cout << "[";
        for(int j=0; j<pt[i].size(); j++){
            cout << pt[i][j];
            if(j<pt[i].size()-1){
            	cout << ",";
            }
        }
        cout << "]";
        if(i<pt.size()-1){
        	cout << ",";
        }
        cout << endl;
    }
    cout << "]" << endl;
}

int main(int argc, char** argv)
{
    int n = 3;
    if (argc>1) {
        n = atoi(argv[1]);
    }
    printTriangle(generate(n)); 
}

#include <vector>

using std::vector; 

class Solution {
public:
    vector<vector<int> > generate(int numRows) {
        vector<vector<int> > vec;
        for (int i=0; i<numRows; ++i) {
            vector<int> row;
            if (!vec.empty()) row.assign(vec.at(i-1).begin(), vec.at(i-1).end());
            row.push_back(1);
            for (int j=i-1; j>0; --j)
                row[j] += row[j-1];
            vec.push_back(row);
        }
        return vec;
    }
};

/// Source : https://leetcode.com/problems/pascals-triangle/description/
/// Author : liuyubobobo
/// Time   : 2018-06-03

#include <iostream>
#include <vector>

using namespace std;


/// Simulation (Dynamic Programming)
/// Time Complexity: O(n^2)
/// Space Complexity: O(1)
class Solution {
public:
    vector<vector<int>> generate(int numRows) {

        vector<vector<int>> res;
        if(numRows <= 0)
            return res;

        res.push_back({1});
        for(int i = 1 ; i < numRows ; i ++){
            vector<int> row;
            row.push_back(1);
            for(int j = 1 ; j < i ; j ++)
                row.push_back(res[i-1][j-1] + res[i-1][j]);
            row.push_back(1);
            res.push_back(row);
        }
        return res;
    }
};

int main() {

    return 0;
}