20. Valid parentheses valid parentheses

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

Given one only includes '(',')','{','}','[',']'  String s , Determines whether the string is valid .

An input string is valid if:

Valid string needs to meet ：

Open brackets must be closed by the same type of brackets.

Opening parentheses must be closed with closing parentheses of the same type .
Open brackets must be closed in the correct order.

The left parenthesis must be closed in the correct order .

Example 1:

Input: s = "()"
Output: true

Example 1：

Input ：s = "()"
Output ：true

Example 2:

Input: s = "()[]{}"
Output: true

Example  2：

Input ：s = "()[]{}"
Output ：true

Example 3:

Input: s = "(]"
Output: false

Example  3：

Input ：s = "(]"
Output ：false

Example  4：

Input ：s = "([)]"
Output ：false

Example  5：

Input ：s = "{[]}"
Output ：true

Constraints:

1 <= s.length <= 104
s consists of parentheses only '()[]{}'.

Tips ：

1 <= s.length <= 104
s Brackets only '()[]{}' form

C Language ：（ Failure ）

bool isValid(char * s){
    int a=0;
    for(int i=0;i<strlen(s);i++)
    {
        if(a[i]=='(')
            a+=1;
        else if(a[i]==')')
            a-=1;
        else if(a[i]=='{')
            a+=2;
        else if(a[i]=='}')
            a-=2;
        else if(a[i]=="[")
            a+=3;
        else if(a[i]=="]")
            a-=3;
    }
    if(a==0)
        return true;
    else
        return false;
}