[860] 柠檬水找零

/*
 * @lc app=leetcode.cn id=860 lang=cpp
 *
 * [860] 柠檬水找零
 */

// @lc code=start
class Solution {
public:
    bool lemonadeChange(vector<int>& bills) {
        int five = 0, ten = 0;
        for(int it : bills)
        {
            if(it == 5)
                five++;
            else if(it == 10)
            {
                if(five == 0){
                    return false;
                }
                five--;
                ten++;
            }
            else
            {
                if(five > 0 && ten > 0){
                    five--;
                    ten--;
                }
                else if (five > 2)
                {
                    five -= 3;
                }
                else 
                {
                    return false;
                }
            }   
        }
        return true;
    }
};
// @lc code=end