From 40059d1b75dd612a29c517ca5173c293c0cb7458 Mon Sep 17 00:00:00 2001
From: Sergiu Ivanov <sivanov@colimite.fr>
Date: Sun, 31 Oct 2021 21:50:19 +0100
Subject: [PATCH] Add min-st-kruskal.

---
 graph.rkt | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/graph.rkt b/graph.rkt
index 75ac80b..ebb681b 100644
--- a/graph.rkt
+++ b/graph.rkt
@@ -37,6 +37,8 @@
            dfs dfs/generalized
            dag? tsort cc cc/bfs scc
 
+           min-st-kruskal
+
            graphviz)
 
   ;; Wrap the opaque graph structure coming from the generic
@@ -182,6 +184,10 @@
   (define (scc g)
     (g:scc (gg g)))
 
+  ;; 5 Spanning Trees
+  (define (min-st-kruskal g)
+    (g:min-st-kruskal (gg g)))
+
   ;; 10 Graphviz
   (define (graphviz g #:output [output #f] #:colors [colors #f])
     (g:graphviz (gg g) #:output output #:colors colors)))
@@ -267,6 +273,9 @@
   [cc/bfs (-> Graph (Listof (Listof Any)))]
   [scc (-> Graph (Listof (Listof Any)))]
 
+  ;; 5 Spanning Trees
+  [min-st-kruskal (-> Graph (Listof (List Any Any)))]
+
   ;; 10 Graphviz
   [graphviz (->* (Graph)
                  (#:output Output-Port
@@ -377,6 +386,13 @@
     (check-equal? (scc (directed-graph '((a b) (b c) (c a) (c d) (e a))))
                   '((e) (c b a) (d))))
 
+  ;; 5 Spanning Trees
+  (test-case "5 Spanning Trees"
+    (define g0 (weighted-graph/undirected '((1 a b) (2 b c) (3 c a) (4 c d) (5 e a))))
+
+    (check-equal? (min-st-kruskal g0)
+                  '((a e) (c d) (c b) (a b))))
+
   (test-case "10 Graphviz"
     (define g (directed-graph '((a b) (b c))))
     (check-equal? (graphviz g)