Added Kosaraju Algorithm in C

Author: keshav2712

classicalAlgos/kosarajusAlgorithm/kosarajus.c

@@ -0,0 +1,142 @@
+#include <stdio.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <assert.h>
+#define N 100
+#define I __INT_MAX__
+
+typedef long long int ll;
+
+typedef struct Node
+{
+    ll vertex;
+    struct Node *next;
+} Node;
+
+void display(Node *first);
+void push(struct Node *first, ll a);
+bool isEmpty(struct Node *first);
+ll pop(struct Node *first);
+
+void display(Node *first)
+{
+
+    struct Node *temp;
+    temp = first->next;
+
+    while (temp)
+    {
+        printf("%lld ", temp->vertex);
+        temp = temp->next;
+    }
+    printf("\n");
+}
+
+void push(struct Node *first, ll a)
+{
+    struct Node *temp = (struct Node *)malloc(sizeof(struct Node));
+    temp->vertex = a;
+    temp->next = first->next;
+    first->next = temp;
+}
+bool isEmpty(struct Node *first)
+{
+    if (first->next)
+        return 0;
+    else
+        return 1;
+}
+
+ll pop(struct Node *first)
+{
+
+    if (isEmpty(first))
+        printf("The stack is empty\n");
+    else
+    {
+
+        Node *p = first;
+        p = p->next;
+        first->next = p->next;
+        ll temp = p->vertex;
+        free(p);
+        return temp;
+    }
+}
+
+void dfsL(Node *list, ll x, ll visited[], Node *st)
+{
+
+    if (visited[x] == 0)
+    {
+        visited[x] = 1;
+        Node *temp;
+        temp = (list + x)->next;
+        while (temp)
+        {
+            dfsL(list, temp->vertex, visited, st);
+            temp = temp->next;
+        }
+        push(st, x);
+    }
+}
+void dfsR(Node *list, ll x, ll visited[])
+{
+
+    if (visited[x] == 0)
+    {
+        visited[x] = 1;
+        printf("%lld ", x);
+        Node *temp;
+        temp = (list + x)->next;
+        while (temp)
+        {
+            dfsR(list, temp->vertex, visited);
+            temp = temp->next;
+        }
+    }
+}
+
+ll main()
+{
+    // for kosarajus
+
+    ll n = 0, X = 0;
+    scanf("%lld %lld", &n, &X);
+    Node *adjList = (Node *)malloc((n + 1) * sizeof(Node));
+    Node *adjListR = (Node *)malloc((n + 1) * sizeof(Node));
+    Node *stack = (Node *)malloc(sizeof(Node));
+    stack->next = NULL;
+    stack->vertex = 0;
+    for (ll i = 0; i <= n; i++)
+    {
+        (adjList + i)->next = NULL;
+        (adjList + i)->vertex = 0;
+        (adjListR + i)->next = NULL;
+        (adjListR + i)->vertex = 0;
+    }
+    ll temp1, temp2;
+    for (ll i = 1; i <= X; i++)
+    {
+        scanf("%lld %lld", &temp1, &temp2);
+        push(adjList + temp1, temp2);
+        push(adjListR + temp2, temp1);
+    }
+    ll visited[N] = {0};
+    for (ll i = 1; i <= n; i++)
+    {
+        if (visited[i] == 0)
+            dfsL(adjList, i, visited, stack);
+    }
+    ll visitedR[N] = {0};
+    while (!isEmpty(stack))
+    {
+        ll i = pop(stack);
+        if (visitedR[i] == 0)
+        {
+            dfsR(adjListR, i, visitedR);
+            printf("\n");
+        }
+    }
+    return 0;
+}