Bag of Tokens | Leetcode #948

class Solution {
public:
    int bagOfTokensScore(vector<int>& tokens, int power) {
        int n = tokens.size();
        sort(tokens.begin(),tokens.end());//sort to make choice-maing obvious

        //2-pointer approach
        int left=0,right=n-1;
        int score = 0,ans = 0;
        while(left<=right){
            while(left<=right and tokens[left]<=power){//greedily score in increasing order of token value
                power-=tokens[left];
                left++;
                score++;
            }
            ans = score;//update new higher score
            if(left<=right and score>0){//get a score from right
                power+=tokens[right];
                right--;
                score--;
            } else {//not possible to get any more score
                break;
            }
        }
        return ans;
    }
};