z

test.lua

@@ -1,79 +0,0 @@
--- adjacency list: adj[u] = {v1, v2, ...}
-local adj = {}
-
-local function add_edge(u, v)
-    adj[u] = adj[u] or {}
-    table.insert(adj[u], v)
-end
-
--- Example graph
-add_edge("A", "B")
-add_edge("B", "C")
-add_edge("C", "D")
--- Uncomment next line to introduce a cycle:
-add_edge("A", "D")
-
----------------------------------------------------------
--- Topological sort (DFS-based, with cycle detection)
----------------------------------------------------------
-local visited = {}  -- "perm" mark: node completely processed
-local in_stack = {} -- "temp" mark: node currently in recursion stack
-local order = {}    -- reverse topological order
-local cycle = nil   -- store cycle if found
-
-local function dfs(u, path)
-    visited[u] = true
-    in_stack[u] = true
-    table.insert(path, u)
-
-    for _, v in ipairs(adj[u] or {}) do
-        if not visited[v] then
-            dfs(v, path)
-            if cycle then return end
-        elseif in_stack[v] then
-            -- found a cycle
-            cycle = {}
-            -- extract the cycle part from path
-            for i = #path, 1, -1 do
-                table.insert(cycle, 1, path[i])
-                if path[i] == v then break end
-            end
-            table.insert(cycle, v) -- close the cycle
-            return
-        end
-    end
-
-    in_stack[u] = false
-    table.remove(path)
-    table.insert(order, 1, u)
-end
-
-local function topo_sort()
-    for u, _ in pairs(adj) do
-        if not visited[u] then
-            dfs(u, {})
-            if cycle then return nil, cycle end
-        end
-    end
-
-    -- build rank map
-    local rank = {}
-    for i, u in ipairs(order) do
-        rank[u] = i
-    end
-    return rank
-end
-
----------------------------------------------------------
--- Run it
----------------------------------------------------------
-local rank, cycle = topo_sort()
-if cycle then
-    print("Cycle detected:")
-    print(table.concat(cycle, " -> "))
-else
-    print("Topological order ranks:")
-    for k, v in pairs(rank) do
-        print(k, v)
-    end
-end