数据结构---数组栈

interface

public interface Stack<E> {
  int getSize();
  boolean isEmpty();
  void push(E e);
  E pop();
  E peek();
}

push、pop、peek

public int getCapacity(){
    return array.getCapacity();
}

@Override
public void push(E e){
    array.addLast(e);
}

@Override
public E pop(){
    return array.removeLast();
}

@Override
public E peek(){
    return array.getLast();
}

实践---> ()[]{}、([)]

   public boolean isValid(String s) {
    ArrayStack<Character> stack = new ArrayStack<>();
    for(int i = 0 ; i < s.length() ; i ++){
        char c = s.charAt(i);
        if(c == '(' || c == '[' || c == '{')
            stack.push(c);
        else{
            if(stack.isEmpty())
                return false;

            char topChar = stack.pop();
            if(c == ')' && topChar != '(')
                return false;
            if(c == ']' && topChar != '[')
                return false;
            if(c == '}' && topChar != '{')
                return false;
        }
    }
    return stack.isEmpty();
}

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