All_pairs_shortest_path.cpp

#include <iostream>
#include <cstdlib>
#define max 10
#define infi 999
using namespace std;
int p[max][max];
void allpairshort(int a[max][max], int n)
{
    int k, i, j;
    for (k = 0; k < n; k++)
    {
        for (i = 0; i < n; i++)
        {
            for (j = 0; j < n; j++)
            {
                if (a[i][k] + a[k][j] < a[i][j])
                {
                    a[i][j] = a[i][k] + a[k][j];
                    p[i][j] = k;
                }
            }
        }
    }
}

void shortest(int i, int j)
{
    int k = p[i][j];
    if (k > 0)
    {
        shortest(i, k);
        cout<<"  "<<k<<"  ";
        shortest(k, j);
    }
}

void findpath(int a[max][max], int i, int j, int n)
{
    if (a[i][j]  < infi)
    {
            cout<<"  "<<i<<"  ";
            shortest(i, j);
            cout<<"  "<<j<<" ";
    }
}

int main()
{
    int i, j, n;
    cout<<"Enter no. of nodes:";
    cin>>n;
    int a[][10] =  {{0, 10, infi, 30, 100},
                {infi, 0 , 50, infi, infi},
                {infi, infi , 0, infi, 10},
                {infi, infi , 20, 0, 60},
                {infi, infi , infi, infi, 0},
                };

    allpairshort(a, n);
    findpath(a, 0, 3, n);
    return 0;
}