Knapsack Conceptual Doubt - Dynamic Programming

[theconqueror]

I'm trying to learn and implement the solution to 0/1 Knapsack Problem and I checked some videos and websites and I'm somewhat confused.

http://www.nitjsr.ac.in/faculty/courses/CA03_2_0-1%20Knapsack%20Problem.pdf
https://www.youtube.com/watch?v=kH7weFvjLPY

However, when I tried to implement it, it didn't work. Please see my implementation below.

#include <iostream>

using namespace std;

int main()
{

    int w[20], v[20], f[20][20], C, n, i=0, j=0;
    cin>>n;
    cin>>C;

    for(i=0; i < n; i++) {
            cout<<"Value: ";cin>>v[i]; cout<<endl;
            cout<<"Weight: "; cin>>w[i]; cout<<endl;
    }

    for(i=0; i <= n; i++) {
            for(j=0; j <= C; j++) {
                    if(i==0 || j == 0)
                        f[i][j]=0;

                            else if(w[i]<=j && i > 0)
                            {
                                    f[i][j]=max(v[i]+f[i-1][j-w[i]], f[i-1][j]);
                            }
                             else
                                f[i][j]=f[i-1][j];
                    }
            }

    for(int i =0; i <= n; i++) {
            for(int j=0; j <= C; j++) {
                    cout<<f[i][j]<<" ";
            }
            cout<<endl;
    }



    return 0;
}

An alternate implementation which uses a different recurrence formula works http://www.geeksforgeeks.org/dynamic-programming-set-10-0-1-knapsack-problem/

What is the difference between the implementation given on GeeksForGeeks based on Wikipedia pseudocode and the implementation above?