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  1. Prepare
  2. Data Structures
  3. Stacks
  4. Maximum Element
  5. Discussions

Maximum Element

  • sasgt97
     + 1 comment

    JAVA

    Approach Maintain a secondary maxStack which will keep track of the last max found.

    Code

    public static List<Integer> getMax(List<String> operations) {
        List<Integer> op = new ArrayList<>();
        Stack<Integer> mainStack = new Stack<>();
        Stack<Integer> maxStack = new Stack<>();
        for(String s : operations){
            if(s.startsWith("1")){
                String[] ss = s.split(" ");
                Integer x = Integer.valueOf(ss[1]);
                //System.out.println(x);
                mainStack.push(x);
                if(maxStack.isEmpty() || x > maxStack.peek()){               
                    maxStack.push(x);            
                }else{
                    maxStack.push(maxStack.peek());
                }
                System.out.println("X "+x+" Max "+maxStack.peek());   
            }else if(s.equals("2")){
                mainStack.pop();
                maxStack.pop(); 
            }else{
                op.add(maxStack.peek());
            }
        }
    return op;
    }

}