算法导论10.1队列

 

注意n个空间的队列，有最多n - 1个元素

 

1

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119

/*  * IA_10.1queue.h  *  *  Created on: Feb 13, 2015  *      Author: sunyj  */   #ifndef IA_10_1QUEUE_H_ #define IA_10_1QUEUE_H_   #include <iostream> #include <cstdint>   // ENQUEUE(Q, x) // Q[Q.tail] = x // if Q.tail = Q.length //     Q.tail = 1 // else Q.tail = Q.tail + 1   // DEQUEUE(Q) // x = Q[Q.haed] // if Q.head == Q.length //     Q.head = 1 // Q.head = Q.head + 1 // return x   template <class T> class queue { public:     queue(int64_t const n) : head(0), tail(0), length(n)     {         data = new T[n]();     }     bool full()     {         if (head == tail + 1 || (0 == head && length == tail + 1))         {             return true;         }         return false;     }     bool empty() { return head == tail; }     void print()     {         if (empty())         {             return ;         }         if (head < tail)         {             for (int64_t i = head; i < tail; i++)             {                 std::cout << data[i] << " ";             }         }         else         {             for (int64_t i = head; i < length; i++)             {                 std::cout << data[i] << " ";             }             for (int64_t i = 0; i < tail; i++)             {                 std::cout << data[i] << " ";             }         }         std::cout << std::endl;         return;     }     int64_t enqueue(T const x)     {         if (full())         {             std::cout << "queue is full, enqueue failed" << std::endl;             return -1;         }         data[tail] = x;         if (length == tail + 1)         {             tail = 0;         }         else         {             ++tail;         }         return 0;     }     int64_t dequeue(T& x)     {         if (empty())         {             return -1;         }         x = data[head];         if (length - 1 == head)         {             head = 0;         }         else         {             ++head;         }         return 0;     }     void clear()     {         while (!empty())         {             T x;             dequeue(x);         }     } private:     int     head;   // points to the first element of the queue, the element has already been in queue     int     tail;   // points to the next coming element     T*      data;     int64_t const length; // the queue can hold at most length-1 element };   #endif /* IA_10_1QUEUE_H_ */

 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34

/*  * IA_10.1queue.cpp  *  *  Created on: Feb 11, 2015  *      Author: sunyj  */ #include "IA_10.1queue.h"   int main() {     queue<int> q(4);     q.enqueue(1);     q.enqueue(2);     q.enqueue(3); // after enqueue 3, the queue is full     q.enqueue(4); // enqueue failed, because the queue is full     q.print();     int x;     if (0 == q.dequeue(x))     {         std::cout << x << std::endl;     }     if (0 == q.dequeue(x))     {         std::cout << x << std::endl;     }     q.print();     q.enqueue(4);     q.enqueue(5);     q.enqueue(6); // enqueue failed, because the queue is full     q.print();    // elements 3, 4, 5     q.clear();     q.print();     return 0; }

1

1

1