题目：

题解：

char pairs(char a) {if (a == '}') return '{';if (a == ']') return '[';if (a == ')') return '(';return 0;
}bool isValid(char* s) {int n = strlen(s);if (n % 2 == 1) {return false;}int stk[n + 1], top = 0;for (int i = 0; i < n; i++) {char ch = pairs(s[i]);if (ch) {if (top == 0 || stk[top - 1] != ch) {return false;}top--;} else {stk[top++] = s[i];}}return top == 0;
}