Wednesday 22 November 2017

C++ Program to Find Shortest Path Between All Vertices Using Floyd-Warshall’s Algorithm


Code:

#include    iostream
#include    cstdlib
#define max 10
#define infi 999
using namespace std;
int p[max][max];
/*
 * All Pairs Shortest Path using Floyd's Algorithm
 */
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;
                }
            }
        }
    }
}

/*
 * Storing the shortest path
 */
void shortest(int i, int j)
{
    int k = p[i][j];
    if (k > 0)
    {
        shortest(i, k);
        cout<<"  "<
        shortest(k, j);
    }
}
/*
 * Display the Shortest Path
 */
void findpath(int a[max][max], int i, int j, int n)
{
    cout<<"Path from " << i <<" to "<< j << ":";
    if (a[i][j]  < infi)
    {
            cout<<"  "<
            shortest(i, j);
            cout<<"  "<
    }
}
/*
 * Main Contains Menu
 */
int main()
{
    int i, j;
    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, 5);
    findpath(a, 0, 4, 5);
    return 0;
}

Output:

Path from 0 to 4:  0    3    2    4

------------------
(program exited with code: 1)
Press return to continue



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