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-rw-r--r--src/main/Toposort.java94
-rw-r--r--src/test/ToposortTest.java108
2 files changed, 190 insertions, 12 deletions
diff --git a/src/main/Toposort.java b/src/main/Toposort.java
index ede04b4..17cebff 100644
--- a/src/main/Toposort.java
+++ b/src/main/Toposort.java
@@ -1,42 +1,45 @@
import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;
+import java.util.Stack;
+import java.util.Arrays;
public class Toposort {
private static ArrayList<Integer> toposort(ArrayList<ArrayList<Integer>> adj) {
- int[] visited = new int[adj.size()];
- ArrayList<Integer> postv = new ArrayList<>(Collections.nCopies(adj.size(),0));
+ boolean[] visited = new boolean[adj.size()];
+ Integer[] postv = new Integer[adj.size()];
int[] clock = new int[1];
dfs(adj, visited, postv, clock);
- ArrayList<Integer> reverse_postv = (ArrayList<Integer>) postv.clone();
- Collections.sort(reverse_postv, Collections.reverseOrder());
+ Integer[] reverse_postv = postv.clone();
+ Arrays.sort(reverse_postv, Collections.reverseOrder());
- ArrayList<Integer> order = new ArrayList<Integer>();
+ ArrayList<Integer> order = new ArrayList<>();
for (int n : reverse_postv) {
- order.add(postv.indexOf(n));
+ order.add(Arrays.asList(postv).indexOf(n));
}
return order;
+
}
- private static void dfs(ArrayList<ArrayList<Integer>> adj, int[] visited, ArrayList<Integer> postv, int[] clock) {
+ private static void dfs(ArrayList<ArrayList<Integer>> adj, boolean[] visited, Integer[] postv, int[] clock) {
for (int v = 0; v < adj.size(); v++) {
- if (visited[v] == 0)
+ if (visited[v] == false)
explore(adj, v, visited, postv, clock);
}
}
- private static void explore(ArrayList<ArrayList<Integer>> adj, int v, int[] visited, ArrayList<Integer> postv, int[] clock) {
- visited[v] = 1;
+ private static void explore(ArrayList<ArrayList<Integer>> adj, int v, boolean[] visited, Integer[] postv, int[] clock) {
+ visited[v] = true;
clock[0] = clock[0] + 1;
for (int n : adj.get(v)) {
- if (visited[n] == 0)
+ if (visited[n] == false)
explore(adj, n, visited, postv, clock);
}
- postv.set(v, clock[0]);
+ postv[v] = clock[0];
clock[0] = clock[0] + 1;
}
@@ -60,5 +63,72 @@ public class Toposort {
System.out.print((x + 1) + " ");
}
}
+
+ static ArrayList<Integer> postOrder(ArrayList<ArrayList<Integer>> adj) {
+ boolean[] visited = new boolean[adj.size()];
+ ArrayList<Integer> postv = new ArrayList<>(Collections.nCopies(adj.size(), 0));
+ int[] clock = new int[1];
+ clock[0] = clock[0] + 1;
+ for (int v = 0; v < adj.size(); v++) {
+ exploreIterative(adj, v, visited, postv, clock);
+ }
+ return postv;
+ }
+
+ private static void exploreIterative(ArrayList<ArrayList<Integer>> adj, int v, boolean[] visited, ArrayList<Integer> postv, int[] clock) {
+ if (visited[v] == false) {
+ // prev[v] = clock[0]
+ boolean[] inStack = new boolean[adj.size()];
+ clock[0] = clock[0] + 1;
+ visited[v] = true;
+ inStack[v] = true;
+ Stack<Integer> vertexStack = new Stack<>();
+ vertexStack.push(v);
+
+ while (vertexStack.isEmpty() == false) {
+ int tempVertex = vertexStack.peek();
+// if (tempVertex != v) {
+// visited[tempVertex] = true;
+// // prev[v] = clock[0]
+// clock[0] = clock[0] + 1;
+// }
+ if (tempVertex != v && visited[tempVertex]) {
+ vertexStack.pop();
+ continue;
+ }
+ if (adj.get(tempVertex).size() == 0) {
+ if (tempVertex != v) {
+ // prev[tempVertex] = clock[0];
+ clock[0] = clock[0] + 1;
+ visited[tempVertex] = true;
+ }
+ postv.set(tempVertex, clock[0]);
+ clock[0] = clock[0] + 1;
+ vertexStack.pop();
+ } else {
+ boolean allEdgesFollowed = true;
+ for (int i : adj.get(tempVertex)) {
+ if (visited[i] == false) {
+// visited[i] = true;
+ // prev[i] = clock[0]
+ if (inStack[i] == false) {
+ inStack[i] = true;
+ vertexStack.push(i);
+ }
+ allEdgesFollowed = false;
+ }
+ }
+ if (allEdgesFollowed) {
+ visited[tempVertex] = true;
+ if (postv.get(tempVertex) == 0)
+ postv.set(tempVertex, clock[0]);
+ clock[0] = clock[0] + 1;
+ vertexStack.pop();
+ }
+ }
+ }
+ }
+ }
+
}
diff --git a/src/test/ToposortTest.java b/src/test/ToposortTest.java
new file mode 100644
index 0000000..e38d3bc
--- /dev/null
+++ b/src/test/ToposortTest.java
@@ -0,0 +1,108 @@
+import org.junit.jupiter.api.Test;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class ToposortTest {
+
+ @Test
+ void test() {
+ ArrayList<ArrayList<Integer>> adj = new ArrayList<>();
+ for (int i = 0; i < 4; i++) {
+ adj.add(new ArrayList<>());
+ }
+
+ adj.get(0).add(1);
+ adj.get(2).add(0);
+ adj.get(3).add(0);
+
+ ArrayList<Integer> results = new ArrayList<Integer>(Arrays.asList(4, 3, 6, 8));
+ assertEquals(results, Toposort.postOrder(adj));
+ }
+
+ @Test
+ void test1() {
+ ArrayList<ArrayList<Integer>> adj = new ArrayList<>();
+ for (int i = 0; i < 5; i++) {
+ adj.add(new ArrayList<>());
+ }
+
+ adj.get(1).add(0);
+ adj.get(1).add(2);
+ adj.get(1).add(3);
+ adj.get(1).add(4);
+
+ adj.get(2).add(0);
+ adj.get(2).add(3);
+ adj.get(2).add(4);
+
+ adj.get(3).add(0);
+ adj.get(3).add(4);
+
+ adj.get(4).add(0);
+
+ ArrayList<Integer> results = new ArrayList<Integer>(Arrays.asList(2, 7, 6, 5, 4));
+ assertEquals(results, Toposort.postOrder(adj));
+ }
+
+ @Test
+ void test2() {
+ ArrayList<ArrayList<Integer>> adj = new ArrayList<>();
+ for (int i = 0; i < 5; i++) {
+ adj.add(new ArrayList<>());
+ }
+
+ adj.get(1).add(0);
+ adj.get(1).add(2);
+ adj.get(1).add(4);
+ adj.get(1).add(3);
+
+ adj.get(2).add(0);
+ adj.get(2).add(3);
+ adj.get(2).add(4);
+
+ adj.get(3).add(4);
+ adj.get(3).add(0);
+
+ adj.get(4).add(0);
+
+ ArrayList<Integer> results = new ArrayList<Integer>(Arrays.asList(2, 7, 6, 5, 4));
+ assertEquals(results, Toposort.postOrder(adj));
+ }
+
+ @Test
+ void test10() {
+ ArrayList<ArrayList<Integer>> adj = new ArrayList<>();
+ for (int i = 0; i < 10; i++) {
+ adj.add(new ArrayList<>());
+ }
+
+ adj.get(9).add(1);
+ adj.get(9).add(7);
+ adj.get(4).add(3);
+ adj.get(2).add(1);
+ adj.get(7).add(3);
+ adj.get(9).add(3);
+ adj.get(0).add(1);
+ adj.get(8).add(6);
+ adj.get(1).add(7);
+ adj.get(2).add(9);
+ adj.get(6).add(5);
+ adj.get(0).add(4);
+ adj.get(0).add(7);
+ adj.get(0).add(5);
+ adj.get(0).add(8);
+ adj.get(2).add(5);
+ adj.get(6).add(9);
+ adj.get(8).add(3);
+ adj.get(8).add(4);
+ adj.get(4).add(2);
+
+ ArrayList<Integer> results = new ArrayList<Integer>(Arrays.asList(13, 7, 9, 5, 10, 3, 11, 6, 12, 8));
+ assertEquals(results, Toposort.postOrder(adj));
+ }
+
+} \ No newline at end of file
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-21 13:27:17 +0000