josephus problem

algorithms/C/linked-lists/josephusProblem.c

@@ -0,0 +1,88 @@
+#include <stdio.h>
+#include <stdlib.h>
+// KHUSHBOO NIJAHWAN
+typedef struct Node{
+    int data;
+    struct Node *next, *prev;
+}node;
+
+node *BML(int n)
+{
+    node *head = NULL;
+    node *ptr =  head, *ptr_prev = head;
+
+    for(int i=0; i<n; i++){
+        if(i == 0){
+            head = (node*)malloc(sizeof(node));
+            head->data = i+1;
+            head->next = head->prev = head;
+            ptr_prev = head;
+        }
+        else{
+            ptr = (node*)malloc(sizeof(node));
+            ptr->data = i+1;
+            ptr_prev->next = ptr;
+            ptr->prev = ptr_prev;
+            ptr_prev = ptr;
+        }
+    }
+    ptr->next = head;
+    head->prev = ptr;
+    return head;
+}
+
+void display(node *head)
+{
+    node *ptr = head;
+    do{
+        printf("%d-> ", ptr->data);
+        ptr = ptr->next;
+    }while(ptr != head);
+    printf("\b\b\b  \n");
+}
+
+void display_rev(node *head)
+{
+    node *ptr = head;
+    do{
+        printf("%d-> ", ptr->data);
+        ptr = ptr->prev;
+    }while(ptr != head);
+    printf("\b\b\b  \n");
+}
+
+int josephus_Khushboo(node *head, int k)
+{
+    display(head);
+    node *ptr = head;
+    if(ptr->next == head)
+        return ptr->data;
+    
+    node *todel=ptr, *todel_prev = todel->prev;
+    for(int i=1; i< k; i++){
+        todel_prev = todel;
+        todel = todel->next;
+    }
+    node *new_head = todel->next;
+    new_head->prev = todel_prev;
+    todel_prev->next = new_head;
+    
+    free(todel);
+    return josephus_Khushboo(new_head, k);
+}
+
+int main()
+{
+    node *head = NULL;
+    int n, k;
+
+    printf("Enter n: ");
+    scanf("%d", &n);
+    head = BML(n);
+    printf("Enter k: ");
+    scanf("%d", &k);
+    printf("Survival: %d\n", josephus_Khushboo(head, k));
+    printf("By Khushboo Nijhawan\n");
+     printf("20BML0035");
+    return 0;
+}