08-27-周三_17-09-29

node_modules/graphlibrary/lib/alg/tarjan.js

@@ -0,0 +1,47 @@
+var _ = require('../lodash')
+
+module.exports = tarjan
+
+function tarjan (g) {
+  let index = 0
+  const stack = []
+  const visited = {} // node id -> { onStack, lowlink, index }
+  const results = []
+
+  function dfs (v) {
+    var entry = visited[v] = {
+      onStack: true,
+      lowlink: index,
+      index: index++
+    }
+    stack.push(v)
+
+    g.successors(v).forEach(function (w) {
+      if (!_.has(visited, w)) {
+        dfs(w)
+        entry.lowlink = Math.min(entry.lowlink, visited[w].lowlink)
+      } else if (visited[w].onStack) {
+        entry.lowlink = Math.min(entry.lowlink, visited[w].index)
+      }
+    })
+
+    if (entry.lowlink === entry.index) {
+      const cmpt = []
+      let w
+      do {
+        w = stack.pop()
+        visited[w].onStack = false
+        cmpt.push(w)
+      } while (v !== w)
+      results.push(cmpt)
+    }
+  }
+
+  g.nodes().forEach(function (v) {
+    if (!_.has(visited, v)) {
+      dfs(v)
+    }
+  })
+
+  return results
+}