Graph-Floyd-Warshall algorithm

#include<bits/stdc++.h>
using namespace std;
int min(int a,int b)
{
    if(a>b)
    return b;
}
int main()
{
    int n,m;
    int u,v,w;
    cin>>n>>m;
    //n # of vertices  m # of edges
     //input format
    // 4 4  <-n,m
    // 0 1 4  <-u,v,w
    // 0 3 5
    // 3 2 3 
    // 2 1 -10
    
    vector<int>temp(n);
    vector<vector<int>>a(n,temp);
    vector<vector<int>>b(n,temp);
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<n;j++)
        {
            if(i==j)
            a[i][j]=0;
            else
            a[i][j]=INT_MAX;
        }
    }
    for(int i=0;i<m;i++)
    {
        cin>>u>>v>>w;
        //replace(a.begin(), myvector.end(), 20, 99)
        a[u][v]=w;
    }
    
    
    //Floyd-Warshall algorithm
    for(int k=0;k<n;k++)
    {
        for(int j=0;j<n;j++)
        {
            for(int i=0;i<n-1;i++)
            {
                b[i][j]=min(a[i][j],a[i][k]+b[k][j]);
            }
        }
        a=b;
    }
    cout<<"\nThe New transive closure Matrix for Graph::";
    for(int i=0;i<n;i++)
    {
        cout<<"\n";
        for(int j=0;j<n;j++)
        cout<<a[i][j]<<" ";
    }
    
    
}