题解 | #有效括号序列#

/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 *
 * @param s string字符串
 * @return bool布尔型
 */
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#define MAX_STACK_SIZE 10000

typedef struct stack {
    char st[MAX_STACK_SIZE];
    int index;
} stack;

void push(stack* a, char s) {
    if (a->index == MAX_STACK_SIZE - 1) {
        exit(1);
    } else {
        a->st[++a->index] = s;
    }
}

char pop(stack* a) {
    if (a->index == -1) {
        exit(1);
    } else return a->st[a->index--];
}

bool isValid(char* s ) {
    stack a = { .index = -1 };
    int length = strlen(s);
    for (int i = 0; i < length; i++) {
        if (s[i] == '[' || s[i] == '{' || s[i] == '(') {
            push(&a, s[i]);
        } else if (s[i] == ']' && (a.index == -1 || a.st[a.index] != '[')) {
            return false;
        } else if (s[i] == '}' && (a.index == -1 || a.st[a.index] != '{')) {
            return false;
        } else if (s[i] == ')' && (a.index == -1 || a.st[a.index] != '(')) {
            return false;
        } else if (s[i] == ']' || s[i] == '}' || s[i] == ')') {
            pop(&a);
        }
    }
    // 如果栈为空，则所有开括号都找到了匹配的闭括号
    return a.index == -1;
}