剑指offer_09 用两个栈实现队列

 //思路在剑指offer书的图里，很容易理解。这里由于c没有API，所以要先定义Stack结构体，不像JavaScript有已经定义好的结构体。并且一些如弹入弹出的操作，也需要自己定义。
 1 typedef struct {
 2     int* stk;
 3     int stkSize;
 4     int stkCapacity;
 5 } Stack;
 6 
 7 Stack* stackCreate(int cpacity) {
 8     Stack* ret = malloc(sizeof(Stack));
 9     ret->stk = malloc(sizeof(int) * cpacity);
10     ret->stkSize = 0;
11     ret->stkCapacity = cpacity;
12     return ret;
13 }
14 
15 void stackPush(Stack* obj, int value) {
16     obj->stk[obj->stkSize++] = value;
17 }
18 
19 void stackPop(Stack* obj) {
20     obj->stkSize--;
21 }
22 
23 int stackTop(Stack* obj) {
24     return obj->stk[obj->stkSize - 1];
25 }
26 
27 bool stackEmpty(Stack* obj) {
28     return obj->stkSize == 0;
29 }
30 
31 void stackFree(Stack* obj) {
32     free(obj->stk);
33 }
34 
35 typedef struct {
36     Stack* inStack;
37     Stack* outStack;
38 } CQueue;
39 
40 CQueue* cQueueCreate() {
41     CQueue* ret = malloc(sizeof(CQueue));
42     ret->inStack = stackCreate(10000);
43     ret->outStack = stackCreate(10000);
44     return ret;
45 }
46 
47 void in2out(CQueue* obj) {
48     while (!stackEmpty(obj->inStack)) {
49         stackPush(obj->outStack, stackTop(obj->inStack));
50         stackPop(obj->inStack);
51     }
52 }
53 
54 void cQueueAppendTail(CQueue* obj, int value) {
55     stackPush(obj->inStack, value);
56 }
57 
58 int cQueueDeleteHead(CQueue* obj) {
59     if (stackEmpty(obj->outStack)) {
60         if (stackEmpty(obj->inStack)) {
61             return -1;
62         }
63         in2out(obj);
64     }
65     int x = stackTop(obj->outStack);
66     stackPop(obj->outStack);
67     return x;
68 }
69 
70 void cQueueFree(CQueue* obj) {
71     stackFree(obj->inStack);
72     stackFree(obj->outStack);
73 }

标签：obj,offer,队列,CQueue,09,ret,int,inStack,Stack
来源： https://www.cnblogs.com/YoungP7/p/16103628.html