44 lines
738 B
C
44 lines
738 B
C
#include <stdio.h>
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#include <stdlib.h>
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typedef struct node_t node_t, *node, *queue;
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struct node_t { int val; node prev, next; };
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#define HEAD(q) q->prev
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#define TAIL(q) q->next
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queue q_new()
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{
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node q = malloc(sizeof(node_t));
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q->next = q->prev = 0;
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return q;
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}
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int empty(queue q)
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{
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return !HEAD(q);
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}
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void enqueue(queue q, int n)
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{
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node nd = malloc(sizeof(node_t));
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nd->val = n;
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if (!HEAD(q)) HEAD(q) = nd;
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nd->prev = TAIL(q);
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if (nd->prev) nd->prev->next = nd;
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TAIL(q) = nd;
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nd->next = 0;
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}
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int dequeue(queue q, int *val)
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{
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node tmp = HEAD(q);
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if (!tmp) return 0;
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*val = tmp->val;
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HEAD(q) = tmp->next;
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if (TAIL(q) == tmp) TAIL(q) = 0;
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free(tmp);
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return 1;
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}
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