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If already a end distance is found, only ways which are shorter are calculated #15

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If already a end distance is found, only ways which are shorter are calculated #15

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35 changes: 20 additions & 15 deletions shortestPath.js
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Original file line number Diff line number Diff line change
Expand Up @@ -34,21 +34,26 @@ const findShortestPath = (graph, startNode, endNode) => {
// find its distance from the start node & its child nodes
let distance = distances[node];
let children = graph[node];
// for each of those child nodes
for (let child in children) {
// make sure each child node is not the start node
if (String(child) === String(startNode)) {
continue;
} else {
// save the distance from the start node to the child node
let newdistance = distance + children[child];
// if there's no recorded distance from the start node to the child node in the distances object
// or if the recorded distance is shorter than the previously stored distance from the start node to the child node
// save the distance to the object
// record the path
if (!distances[child] || distances[child] > newdistance) {
distances[child] = newdistance;
parents[child] = node;

// if already a end distance is found, we allow only ways which are shorter
if (!distances[endNode] || distances[endNode] > distance) {
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This line is new

// for each of those child nodes
for (let child in children) {
// make sure each child node is not the start node
if (String(child) === String(startNode)) {
continue;
} else {
// save the distance from the start node to the child node
let newdistance = distance + children[child];
// if there's no recorded distance from the start node to the child node in the distances object
// or if the recorded distance is shorter than the previously stored distance from the start node to the child node
// save the distance to the object but if already a end distance is found, it must be shorter then it
// record the path
if ((!distances[child] || distances[child] > newdistance)
&& (!distances[endNode] || distances[endNode] > newdistance)) {
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and this line is new

distances[child] = newdistance;
parents[child] = node;
}
}
}
}
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49 changes: 27 additions & 22 deletions shortestPathWithLogs.js
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Original file line number Diff line number Diff line change
Expand Up @@ -34,29 +34,34 @@ const findShortestPathWithLogs = (graph, startNode, endNode) => {
// find its distance from the start node & its child nodes
let distance = distances[node];
let children = graph[node];
// for each of those child nodes
for (let child in children) {
// make sure each child node is not the start node
if (String(child) === String(startNode)) {
console.log("don't return to the start node! 🙅");
continue;
} else {
console.log("startNode: " + startNode);
console.log("distance from node " + parents[node] + " to node " + node + ")");
console.log("previous distance: " + distances[node]);
// save the distance from the start node to the child node
let newdistance = distance + children[child];
console.log("new distance: " + newdistance);
// if there's no recorded distance from the start node to the child node in the distances object
// or if the recorded distance is shorter than the previously stored distance from the start node to the child node
// save the distance to the object
// record the path
if (!distances[child] || distances[child] > newdistance) {
distances[child] = newdistance;
parents[child] = node;
console.log("distance + parents updated");

// if already a end distance is found, we allow only ways which are shorter
if (!distances[endNode] || distances[endNode] > distance) {
// for each of those child nodes
for (let child in children) {
// make sure each child node is not the start node
if (String(child) === String(startNode)) {
console.log("don't return to the start node! 🙅");
continue;
} else {
console.log("not updating, because a shorter path already exists!");
console.log("startNode: " + startNode);
console.log("distance from node " + parents[node] + " to node " + node + ")");
console.log("previous distance: " + distances[node]);
// save the distance from the start node to the child node
let newdistance = distance + children[child];
console.log("new distance: " + newdistance);
// if there's no recorded distance from the start node to the child node in the distances object
// or if the recorded distance is shorter than the previously stored distance from the start node to the child node
// save the distance to the object but if already a end distance is found, it must be shorter then it
// record the path
if ((!distances[child] || distances[child] > newdistance)
&& (!distances[endNode] || distances[endNode] > newdistance)) {
distances[child] = newdistance;
parents[child] = node;
console.log("distance + parents updated");
} else {
console.log("not updating, because a shorter path already exists!");
}
}
}
}
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