Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

The brackets must close in the correct order, "()" and "()[]{}" are all valid but "(]" and "([)]" are not.

題目大意：給定一個字串只包含“(){}[]”,判斷該字串的括號是否匹配

思路：利用棧的思想，不匹配入棧，匹配出棧，最後檢視棧頂

#include <string.h>

bool isValid(char* s) {
    int len = strlen(s);
    char *p = malloc(len);
    int top = 0;    //從下標1開始儲存
    
    if(!p)
        return false;
    memset(p, 0x0, len);
    while(*s)
    {
        //檢視assic碼，得知匹配情況的assic碼差值
        if(*s - p[top] == 1 || *s - p[top] == 2)
        {
            p[top] = 0;
            top--;
        }
        else
        {
            top++;
            p[top] = *s;

        }
        s++;
    }
    free(p);
    return (top ? false : true);
}