08-27-周三_17-09-29

node_modules/graphlibrary/lib/alg/floyd-warshall.js

@@ -0,0 +1,50 @@
+var _ = require('../lodash')
+
+module.exports = floydWarshall
+
+var DEFAULT_WEIGHT_FUNC = _.constant(1)
+
+function floydWarshall (g, weightFn, edgeFn) {
+  return runFloydWarshall(g,
+    weightFn || DEFAULT_WEIGHT_FUNC,
+    edgeFn || function (v) { return g.outEdges(v) })
+}
+
+function runFloydWarshall (g, weightFn, edgeFn) {
+  const results = {}
+  const nodes = g.nodes()
+
+  nodes.forEach(function (v) {
+    results[v] = {}
+    results[v][v] = { distance: 0 }
+    nodes.forEach(function (w) {
+      if (v !== w) {
+        results[v][w] = { distance: Number.POSITIVE_INFINITY }
+      }
+    })
+    edgeFn(v).forEach(function (edge) {
+      const w = edge.v === v ? edge.w : edge.v
+      const d = weightFn(edge)
+      results[v][w] = { distance: d, predecessor: v }
+    })
+  })
+
+  nodes.forEach(function (k) {
+    var rowK = results[k]
+    nodes.forEach(function (i) {
+      var rowI = results[i]
+      nodes.forEach(function (j) {
+        var ik = rowI[k]
+        var kj = rowK[j]
+        var ij = rowI[j]
+        var altDistance = ik.distance + kj.distance
+        if (altDistance < ij.distance) {
+          ij.distance = altDistance
+          ij.predecessor = kj.predecessor
+        }
+      })
+    })
+  })
+
+  return results
+}