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DS/C/Lab/Shortcodes/dcll.c

@@ -0,0 +1,54 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct c { int d; struct c *n, *p; } *C;
+C l = NULL;
+
+C new_c(int v) {
+    C t = (C)malloc(sizeof(struct c));
+    t->d = v; t->n = t->p = NULL; return t;
+}
+
+void insert_beg(int v) {
+    C t = new_c(v);
+    if (!l) { l = t; l->n = l->p = l; }
+    else {
+        t->n = l->n;
+        l->n->p = t;
+        t->p = l;
+        l->n = t;
+    }
+}
+
+void del_end() {
+    if (!l) printf("List is empty");
+    else {
+        C p = l->p;
+        p->n = l->n;
+        l->n->p = p;
+        free(l);
+        l = p;
+    }
+}
+
+void traverse() {
+    if (!l) return;
+    C c = l->n;
+    do { printf("%d ", c->d); c = c->n; } while (c != l->n);
+    printf("\n");
+}
+
+int main() {
+    char cont = 'y'; int ch;
+    while (cont == 'y') {
+        printf("1. Insert at beginning\n2. Delete at end\n3. Traverse\n");
+        scanf("%d", &ch);
+        if (ch == 1) { int v; scanf("%d", &v); insert_beg(v); }
+        else if (ch == 2) { del_end(); printf("Element deleted\n"); }
+        else if (ch == 3) { traverse(); }
+        printf("Continue? (y/n)\n");
+        fflush(stdin);
+        scanf(" %c", &cont);
+    }
+    return 0;
+}