FloydWarshal with path tracing

Author: coderick14

floydWarshal.cpp

@@ -0,0 +1,88 @@
+#include <bits/stdc++.h>
+#define INF INT_MAX
+#define ll long long
+#define N 100
+using namespace std;
+
+ll dist[N][N], path[N][N];
+
+void printPath(ll i, ll j) {
+    //cout<<"Printing path from "<<i<<" to "<<j<<endl;
+    stack<ll> stk;
+    stk.push(j);
+    while(path[i][j] != i && path[i][j] != -1) {
+        stk.push(path[i][j]);
+        j = path[i][j];
+    }
+    if(path[i][j] == -1) {
+        cout<<"No path exists\n";
+    }
+    else {
+        stk.push(i);
+        while(!stk.empty()) {
+            cout<<stk.top()<<" ";
+            stk.pop();
+        }
+        cout<<"\n";
+    }
+}
+
+int main() {
+    ll i,j,k,n,e,u,v,w;
+    cin>>n>>e;
+    for(i=0; i<=n; i++) {
+        for(j=0; j<=n; j++) {
+            if(i==j) {
+                dist[i][j] = 0;
+                path[i][j] = i;
+            }
+            else {
+                dist[i][j] = INF;
+                path[i][j] = -1;
+
+            }
+        }
+    }
+
+    for(i=0; i<e; i++) {
+        cin>>u>>v>>w;
+        dist[u][v] = w;
+        //dist[v][u] = w; //uncomment for undirected graph
+        path[u][v] = u;
+    }
+
+    for(k=1; k<=n; k++) {
+        for(i=1; i<=n; i++) {
+            for(j=1; j<=n; j++) {
+                if(dist[i][k] != INF && dist[k][j] != INF && dist[i][k] + dist[k][j] < dist[i][j]) {
+                    dist[i][j] = dist[i][k] + dist[k][j];
+                    path[i][j] = path[k][j];
+                    //cout<<i<<" ---> "<<k<<" ---> "<<j<<" dist = "<<dist[i][j]<<endl;
+                }
+            }
+        }
+    }
+
+    cout<<"Distance Matrix\n";
+    for(i=1; i<=n; i++) {
+        for(j=1; j<=n; j++) {
+            if(dist[i][j] == INF)
+                cout<<"INF ";
+            else
+                cout<<dist[i][j]<<" ";
+        }
+        cout<<endl;
+    }
+    cout<<"Path Matrix\n";
+    for(i=1; i<=n; i++) {
+        for(j=1; j<=n; j++) {
+            cout<<path[i][j]<<" ";
+        }
+        cout<<endl;
+    }
+    for(i=1; i<=n; i++) {
+        for(j=1; j<=n; j++)
+            printPath(i,j);
+    }
+    return 0;
+}