棧的應用---平衡符號

判斷一行字串輸入"各種括號"是否是合法的-----------------------棧用陣列實現

如：[()]是合法的(balance)

[(])是不合法的(imbalance)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct Mystack *Stack;

struct Mystack {
    int Capacity;       /* 棧的容量 */
    int Top_of_stack;   /* 棧頂下標 */
    char *Array;        /* 存放棧中元素的陣列 */
};

/* 棧的建立 */
Stack CreateStack(int Max)
{
    Stack S;
    S = malloc(sizeof(struct Mystack));
    if (S == NULL)
        printf("Create stack error!\n");

    S->Array = malloc(sizeof(char) * Max);
    if (S->Array == NULL)
        printf("Create stack error!\n");

    S->Capacity = Max;
    S->Top_of_stack = 0;
    return S;
}

/* 釋放棧 */
void DisposeStack(Stack S)
{
    if (S != NULL)
    {   
        free(S->Array);
        free(S);
    }   
}

/* 判斷一個棧是否是空棧 */
int IsEmpty(Stack S)
{
    return !S->Top_of_stack;
}

/* 判斷一個棧是否滿棧 */
int IsFull(Stack S)
{
    if (S->Top_of_stack == S->Capacity - 1)
        return 1;
    else
        return 0;
}


/* 資料入棧 */
int Push(int x, Stack S)
{
    if (IsFull(S))
        printf("The Stack is full!\n");
    else
        S->Array[S->Top_of_stack++] = x;
}

/* 資料出棧 */
int Pop(Stack S)
{
    if (IsEmpty(S))
        printf("The Stack is empty!\n");
    else
        S->Top_of_stack--;
}

/* 將棧頂返回 */
char Top(Stack S)
{
    if (!IsEmpty(S))
        return S->Array[S->Top_of_stack-1];
    printf("The Stack is empty!\n");
    return 0;
}

int main()
{
    int i, len;
    char str[100];
    printf("Please input the symbol that you want to balance: \n");
    scanf("%s", str);
    len = strlen(str);
    /* 根據序列的長度來建立棧 */
    struct Mystack *my_stack = CreateStack(len+1);
    for (i = 0; i < len; i++)
    {
        if (str[i] == '{' || str[i] == '[' || str[i] == '(' )
            Push(str[i], my_stack);
        if (str[i] == '}')
        {
            if (Top(my_stack) == '{')
                Pop(my_stack);
            else
                break;
        }
        else if (str[i] == ']')
        {
            if (Top(my_stack) == '[')
                Pop(my_stack);
            else
                break;
        }
        else if (str[i] == ')')
        {
            if (Top(my_stack) == '(')
                Pop(my_stack);
            else
                break;
        }
    }
    /* 如果最後佔空則序列是合法的 */
    if(IsEmpty(my_stack))
        printf("The symbol that you input is balance!\n");
    else
        printf("The symbol that you input is imbalance!\n");
    DisposeStack(my_stack);
    return 0;
}

測試：

shang@shang:~/C$ ./a.out 
Please input the symbol that you want to balance: 
{[]}
The symbol that you input is balance!
shang@shang:~/C$ ./a.out 
Please input the symbol that you want to balance: 
[(])
The symbol that you input is imbalance!
shang@shang:~/C$ ./a.out 
Please input the symbol that you want to balance: 
([{}])
The symbol that you input is balance!
shang@shang:~/C$