Stack栈——application of stack

判断括号表达式是否平衡

1. 平衡：example：{[]}()
2. 不平衡：example:{[}](

判断要push的是否为括号的开始符号，也就是'(' '{' '['。如果是则push栈中，反之若是')' '}' ']',则判断栈是否为空，如果是空直接返回 no balance，若不为空c = pop栈，并与c进行匹配，匹配成功，就进行下一次的插入，反之 返回 no balance。

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

struct stack
{
    int data;
    struct stack * next;
};
int matchParenthese(int c1, int c2)
{
    if('(' == c1 && ')' == c2)
    {
        return 1;
    }
    else if('[' == c1 && ']' == c2)
    {
        return 1;
    }
    else if('{' == c1 && '}' == c2)
    {
        return 1;
    }
    else
    {
        return 0;
    }
}
int judgeParenthese(char ex[])
{
    struct stack * s = NULL;
    int index = 0;

    while(ex[index])
    {
        if('(' == ex[index] || '[' == ex[index] || '{' == ex[index])
        {
            push(&s, ex[index]);
        }
        else if(')' == ex[index] || ']' == ex[index] || '}' == ex[index])
        {
            if(NULL == s)
            {
                printf("
The stack is empty");
                return 0;
            }
            else if(!(matchParenthese(pop(&s), ex[index])))
            {
                return 0;
            }

        }
        index++;
    }
    if(NULL == s)
    {
        return 1;
    }
    else
    {
        return 0;
    }
}
struct stack * newNode(int data)
{
    struct stack * new_node = (struct stack *)malloc(sizeof(struct stack));
    new_node->data = data;
    new_node->next = NULL;

    return new_node;
}
void push(struct stack ** root, int data)
{
    struct stack * new_node = newNode(data);

    new_node->next = (*root);
    (*root) = (new_node);
    printf("
 %c pushed to stack", data);
}
int isEmpty(struct stack * root)
{
    return NULL == root ? 1 : 0;
}
int pop(struct stack ** root)
{
    if(isEmpty((*root)))
    {
        printf("
UnderFlow");
        return 0;
    }
    struct stack * temp = (*root);
    int data = temp->data;
    (*root) = temp->next;
    free(temp);
    printf("
 The %c poped of stack", data);
    return data;
}
int peek(struct stack * root)
{
    if(isEmpty(root))
    {
        printf("
UnderFlow");
        return 0;
    }
    return root->data;
}
int main(void)
{
    char ex[] = "{()}[";
    if(judgeParenthese(ex))
    {
        printf("
Balance!");
    }
    else
    {
        printf("
NO!");
    }
    return 0;
}