21. Find the Most Competitive Subsequence

class Solution {
    public int[] mostCompetitive(int[] nums, int k) {
        Stack<Integer> st=new Stack<>();
      
        for(int i=0;i<nums.length;i++){
            
            //poping from stack
            while(!st.isEmpty() && nums[i]<nums[st.peek()] && st.size() + nums.length -i>k){
                st.pop();
            }
            if(st.size()<k){
                st.push(i);
            }
        }
        
        int i=k;
        int[] result= new int[k];
        while(!st.isEmpty()){
            result[--i]=nums[st.pop()];
        }
        
        return result;
    }
}

class Solution {
    public int[] mostCompetitive(int[] nums, int k) {
        int[] result= new int[k];
        int top=0;
        for(int i=0;i<nums.length;i++){
            
            //poping from stack
            while(top>0 && nums[i]<nums[top-1] && (top + nums.length -i)>k){
                top--;
            }
            
            if(top<k){
                result[top++]=nums[i];
            }
        }
        return result;
    }
}