08-27-周三_17-09-29

node_modules/graphlib/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) {
+  var results = {};
+  var 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) {
+      var w = edge.v === v ? edge.w : edge.v;
+      var 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;
+}