Valid Parentheses — Stack Bracket Matching

// C
bool isValid(char* s) {
    char stack[10001]; int top = 0;
    for (int i = 0; s[i]; i++) {
        if (s[i]=='(' || s[i]=='{' || s[i]=='[') stack[top++]=s[i];
        else {
            if (!top) return false;
            char c = stack[--top];
            if ((s[i]==')' && c!='(') || (s[i]==']' && c!='[') || (s[i]=='}' && c!='{'))
                return false;
        }
    }
    return top == 0;
}

// C++
bool isValid(string s) {
    stack<char> st;
    for (char c : s) {
        if (c=='(' || c=='{' || c=='[') st.push(c);
        else {
            if (st.empty()) return false;
            char top = st.top(); st.pop();
            if ((c==')' && top!='(') || (c==']' && top!='[') || (c=='}' && top!='{'))
                return false;
        }
    }
    return st.empty();
}

// Java
public boolean isValid(String s) {
    Deque<Character> stack = new ArrayDeque<>();
    for (char c : s.toCharArray()) {
        if (c=='(' || c=='{' || c=='[') stack.push(c);
        else {
            if (stack.isEmpty()) return false;
            char top = stack.pop();
            if ((c==')' && top!='(') || (c==']' && top!='[') || (c=='}' && top!='{'))
                return false;
        }
    }
    return stack.isEmpty();
}

# Python
def isValid(s):
    stack = []
    mapping = {')':'(', ']':'[', '}':'{'}
    for c in s:
        if c in mapping:
            if not stack or stack[-1] != mapping[c]: return False
            stack.pop()
        else:
            stack.append(c)
    return not stack