另類迴圈佇列
阿新 • • 發佈:2018-11-08
裁判測試程式樣例:
#include <stdio.h> #include <stdlib.h> #define ERROR -1 typedef int ElementType; typedef enum { addq, delq, end } Operation; typedef enum { false, true } bool; typedef int Position; typedef struct QNode *PtrToQNode; struct QNode { ElementType *Data; /* 儲存元素的陣列 */ Position Front;/* 佇列的頭、尾指標 */ int Count; /* 佇列中元素個數 */ int MaxSize; /* 佇列最大容量 */ }; typedef PtrToQNode Queue; Queue CreateQueue( int MaxSize ) { Queue Q = (Queue)malloc(sizeof(struct QNode)); Q->Data = (ElementType *)malloc(MaxSize * sizeof(ElementType)); Q->Front = 0; Q->Count = 0; Q->MaxSize = MaxSize; return Q; } bool AddQ( Queue Q, ElementType X ); ElementType DeleteQ( Queue Q ); Operation GetOp(); /* 裁判實現,細節不表 */ int main() { ElementType X; Queue Q; int N, done = 0; scanf("%d", &N); Q = CreateQueue(N); while ( !done ) {switch( GetOp() ) { case addq: scanf("%d", &X); AddQ(Q, X); break; case delq: X = DeleteQ(Q); if ( X!=ERROR ) printf("%d is out\n", X); break; case end: while (Q->Count) printf("%d ", DeleteQ(Q)); done = 1; break; } } return 0; } /* 你的程式碼將被嵌在這裡 */
解題思路: Q->Front指向首元素位置,Q->Count作為偏移量
1 bool AddQ( Queue Q, ElementType X ) 2 { 3 if(Q->Count == Q->MaxSize) 4 { 5 printf("Queue Full\n"); 6 return false; 7 } 8 Q->Data[(Q->Front + Q->Count) % Q->MaxSize] = X; 9 Q->Count++; 10 return true; 11 } 12 ElementType DeleteQ( Queue Q ) 13 { 14 if(Q->Count == 0) 15 { 16 printf("Queue Empty\n"); 17 return ERROR; 18 } 19 ElementType tmp = Q->Data[Q->Front]; 20 Q->Front = (Q->Front + 1) % Q->MaxSize; 21 Q->Count--;
22 return tmp; 23 }