Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.
An input string is valid if:
- Open brackets must be closed by the same type of brackets.
- Open brackets must be closed in the correct order.
- Every close bracket has a corresponding open bracket of the same type.
Example 1
Input: s = "()"
Output: true
Example 2
Input: s = "()[]{}"
Output: true
Example 3
Input: s = "(]"
Output: false
Constraints
- 1 <= s.length <= 10e4
- s consists of parentheses only '()[]{}'.
Solution
- 首先应该特判，如果括号个数为奇数个显然无法匹配
- 进行模拟出入栈操作，当前字符能够和栈顶匹配，共同出栈，否则入栈。
bool isValid(char * s){
int n = strlen(s);
if (n % 2) return false;
char stack[10000];
int top = 1;
stack[0] = s[0];
for (int i = 1; i < n; i++) {
if (!top) stack[top++] = s[i];
else if (stack[top - 1] == '(' && s[i] == ')') top--;
else if (stack[top - 1] == '[' && s[i] == ']') top--;
else if (stack[top - 1] == '{' && s[i] == '}') top--;
else stack[top++] = s[i];
}
return !top;
}
